Solid A is 4.0g oxalic acid COOH 2 2H2O accurately measured and placed in a stoppered boiling tube 2. Solution B is 0.25M NaOH prepared by dissolving 10g NaOH pellets in 600cm3 of water and topping up to 100cm3 solution with distilled water 3. Solution C is prepared by dissolving a mixture of aluminium nitrate and sodium sulphite NaSO3 i.e 10g aluminum nitrate and 10g sodium sulphate in 600cm3 of distilled water and topping up to 1000cm3 solution with distilled water 4. Solid D is maleic acid 5. Potassium iodide is prepared by dissolving 21.4g of solid K in 1000cm3 of solution Prepare the quantity you require 6. 2M ammonia solution is prepared by dissolving 123cm3 of ammonia in 1000cm3 of ammonium hydroxide solution 7. 2M NaOH is prepared by dissolving 80g of HaOH pellets in 1000cm3 of solution 8. Lead II nitrate solution is prepared by dissolving 33.1g of Lead II nitrate in 1000cm3 of solution Prepare the quantity you require 9. Barium nitrate solution is prepared by dissolving 26.1g of solid barium nitrate in 1000cm3 of solution prepare the quantity you require 10. Nitric V acid is prepared by dissolving 145cm3 of concentrated nitric V acid in 1000cm3 of solution prepare the quantity you require 11. KMnO4 is prepared by dissolving 3.2g KMnO4 in 400cm3 of 2.0M sulphuric VI acid and topping up to 1000cm3 of solution using distilled water 12. Bromine water of prepared by dissolving 1cm3 of bromine water is a fumed chamber. Www.freekcsepastpapers.comPage 86 IMENTI SOUTH EXAMINATIONS, 2023 Kenya Certificate of Secondary Education 233 3 CHEMISTRY PAPER 3 PRACTICAL TIME: 214 HOURS INSTRUCTIONS Read the procedure carefully, perform the experiments and answer the questions.


KMnO4 is prepared by dissolving 3.2g KMnO4 in 400cm3 of 2.0M sulphuric VI acid and topping up to 1000cm3 of solution using distilled water 12. Bromine water of prepared by dissolving 1cm3 of bromine water is a fumed chamber. Www.freekcsepastpapers.comPage 86 IMENTI SOUTH EXAMINATIONS, 2023 Kenya Certificate of Secondary Education 233 3 CHEMISTRY PAPER 3 PRACTICAL TIME: 214 HOURS INSTRUCTIONS Read the procedure carefully, perform the experiments and answer the questions. The first 15minutes of the 214 hours allowed for this paper are meant for reading through the paper to confirm that all the apparatus and reagents are provided. Mathematical tables and electronic calculators may be used. All working must be clearly shown where necessary. Question 1 You are provided with, Solid A 4.0g COOH 2 XH2O Solution B 0.25M NaoH You are supposed to i Determine the solubility of A at different temperatures. Ii Determine the amount of water of crystallization X in solid A. Procedure A Into the boiling tube containing solid A, add 4cm3 of distilled water. Using a 10ml measuring cylinder. Stir with the thermometer while heating the mixture until all the solid dissolves. Withdraw from heat and allow the mixture to cool while stirring you may use a water bath . Record the temperature at which crystals 1st appear in the table I below. Add 2cm3 more of distilled water to make a total of 6cm3 and repeat the above procedure. Repeat the above procedure two 2 more times and complete table I below. RETAIN the content of boiling tube for procedure B. Table 1 Volume of water added 4 6 8 10 Solubility g 100g of water Temperature at which crystals appear 6 marks i Plot a graph of solubility of A against temperature. 3 marks ii From your graph determine the solubility of A at 60oC. 1 mark Procedure B Transfer the content of the boiling tube into a 250ml volumetric flask. Add distilled water upto the mark.


Complete the table below by selecting the appropriate pH for each substance from pH values 1.0, 4.0, 7.0 and 11. 3mks Substance pH Sodium carbonate Lemon juice Sodium chloride 4. The structure below represents a portion of an additional polymer. A Draw the structure of monomer. 1mk b If the portion of the polymer has a relative molecular mass of 1000, calculate the number of monomer in the portion. 2mks 5. You are provided with the following: copper turnings, dilute sulphuric VI acid and source of heat. Describe fully how you would prepare copper II sulphate crystals 3mks 6. The set up below was used to study the reaction between ammonia and air in the absence of a catalyst. A State the observation in the above set up. 1mk www.freekcsepastpapers.comPage 97 b What condition is necessary for ammonia to burn as shown above? 1mk . C Write an equation for the burning of ammonia 1mk 7. The table below shows properties of chloride of period 3 elements. Study and answer the questions that follow. Chloride Mpt 0c Bpt 0c Physical state at room temperature. Sodium chloride 801 1467 Solid Magnesium chloride 714 1437 Solid Aluminium chloride 180 Sublimes Solid Phosphorus v chloride 32 -75 Liquid a Explain why sodium chloride has a high melting point and boiling point while aluminium chloride sublimes 2mks b Compare the nature of the solution formed when both magnesium chloride and aluminium chloride are dissolved in water. Explain. 2mks 8. When gas A is heated at constant pressure its volume changes as shown in the sketch below. A Name the law that gas A obeys. 1mk b A certain mass of a gas has volume of 271cm3 at 310k and 750mmHg pressure. Calculate the temperature in 00c that the same gas would occupy 283cm3 at 750mmHg pressure. 2mks 9. Study the set-up of apparatus below and answer the questions that follow.


Calculate the temperature in 00c that the same gas would occupy 283cm3 at 750mmHg pressure. 2mks 9. Study the set-up of apparatus below and answer the questions that follow. A Write the equation for the reaction that occur in tube V 1mk b State one industrial use of gas W 1mk c Name another metal that can be used in tube V instead of magnesium. 1mk 10. The following chemical tests were carried out on separate sample of solution labelled A. The observations made were recorded as shown below. Test Observation i Addition of sodium hydroxide White precipitate soluble in excess ii Addition of ammonium hydroxide White precipitate insoluble in excess iii Addition of hydrochloric acid Effervescence iv Addition of acidified potassium manganite VII Its color remains purple a Identify the possible ions present in solution A. 1mk b Write the formula of the compound formed in chemical test i 1mk c State one application of a complex ion. 1mk www.freekcsepastpapers.comPage 98 11. Iron objects can corrode when exposed to the atmosphere. I Corrosion involves the oxidation of iron .State what is meant by oxidation. 1mk ii Painting iron objects prevents corrosion. Explain how painting prevents iron from corrosion. 1mk iii Corrosion of iron objects can be prevented by painting or electroplating. State another way that can prevent corrosion. 1 mk 12. Dry ammonia gas was passed through heated oxide of lead of mass 4.78g until there was no further change. The mass of the residue was found to be 4.14g. Determine the formula of the oxide if its molecular mass is 239g. Pb 207, O 16 3mk 13. The schematic diagram for the manufacture of sodium carbonate is shown below. A Write an equation for the reaction of formation of ammonium chloride and substance A. 1mk b State how the following are carried out i Process 1 1mk ii Process 2 1mk 14. The table below shows the solubility of salt X at various temperatures.


A Write an equation for the reaction of formation of ammonium chloride and substance A. 1mk b State how the following are carried out i Process 1 1mk ii Process 2 1mk 14. The table below shows the solubility of salt X at various temperatures. Temperature 0c Solubility g 100g of H2O 0 36 40 30 80 25 100 i A saturated solution of the salt at 400c was heated at 1000c. State and explain the observation made. 1mk ii Calculate the mass of salt formed when a saturated solution of the salt at 00c is heated to 1000c. 1mk 15. The figure below shows the apparatus used by students to study the electrolysis of molten lead II iodide. A In the diagram label the anode. 1mk b When the switch was on, the bulb did not light. Explain. 1mk c State and explain the observation made at the anode. 1mk www.freekcsepastpapers.comPage 99 16. The table below shows information about some hydrocarbons complete the table to show the names and structures of these hydrocarbons 3mks Name Structure Name Structure i ii iii 3- Methylpentane 17. A Hydrogen sulphide gas was bubbled into an aqueous solution of iron ii chloride. State and explain the observations made. 2mks b Write the equation for the reaction that took place 1mk 18. Excess magnesium powder was added to 25cm3 of 1M copper ii chloride solution. The temperature of solution increased by 430c. Density of solution 1g cm3, specific heat capacity 4.2 J g K Determine; a The heat of reaction 1mk b The molar heat of displacement of copper 2mk 19. The grid below is part of the periodic to table. Use it to answer the question that follow.


Density of solution 1g cm3, specific heat capacity 4.2 J g K Determine; a The heat of reaction 1mk b The molar heat of displacement of copper 2mk 19. The grid below is part of the periodic to table. Use it to answer the question that follow. The letters are not the actual symbol of the elements P S T W X M Y R Z a Draw a dot and cross x diagram to show the structure of elements T, 1mk b Write an equation for the reaction that occurs when element R in solid form react with an aqueous solution containing ions of element P 1mk c J is an element that belongs to the 4th period of the periodic table and reacts by gaining one electron. Show the position of J in the grid. 1mk 20. 15.7 g of an organic acid RCOOH was dissolved in 600cm3 of water and more water added to make one litre of solution. 25.0cm3 of this solution was found to require 21.5cm3 of 0.207 M potassium hydroxide solution for complete neutralization. C 12, O 16, H 1 i Determine the formula mass of the acid 3mks ii Calculate the mass of R 1mk 21. The set up below shows the apparatus for preparation of nitrogen i oxide. I Name solid X 1mk ii What precaution is taken when heating solid X 1mk b Nitrogen i oxide doesn t burn but a burning magnesium ribbon continues burning in the gas. Explain 1mk www.freekcsepastpapers.comPage 100 22. Study the flow chart below and answer the questions that follow. A Name substance Y and Z 1mk b Write an equation for the formation of solid X 1mk c State one use of solution C 1mk 23. A Phosphorous has a melting point of 440C or 5900C . Explain 1mk b Why is phosphorous stored under water 1mk c Using dot and cross diagrams, draw the structure of aluminium oxide 1mk 24. A gold rings contain 3.94g of gold.


A Phosphorous has a melting point of 440C or 5900C . Explain 1mk b Why is phosphorous stored under water 1mk c Using dot and cross diagrams, draw the structure of aluminium oxide 1mk 24. A gold rings contain 3.94g of gold. Calculate the number of gold atoms in the ring. Avogadro s constant 6.02 1023, Au 197 2mks 25. A student accidentally placed a small amount of charcoal in a solution labelled concentrated nitric v acid. A State and explain the observation made 2mk b Write the equation for the reaction 1mk 26. A Name two reagents that are used to prepare ethyne 1mk b Propanol and butanol are third and fourth members respectively of the same homologous series. State and explain how their boiling points compare. 2mks 27 Using a well labelled diagram show how to prepare and collect dry sulphur iv oxide starting with copper turnings. 2mks www.freekcsepastpapers.comPage 101 CEKENAS PREMOCK EXAMINATION, 2023 Kenya Certificate of Secondary Education 233 2 CHEMISTRY PAPER 2 TIME: 2 HOURS INSTRUCTION TO THE CANDIDATES 1. All working must be clearly shown where necessary. 2. Mathematical tables and silent electronic calculations may be used 1. A The grid below shows part of the periodic table. Study it and answer the questions that follow. Letters do not represent the actual symbols E S P U V M X Y N i Select an element which forms an ion with a charge of -3 1mark ii Name the type of structure that the chloride of Y would have. Explain 2marks iii How does the reactivity of M compare with that of N. Explain 2marks iv 1.3g of P completely burns in chlorine and consumes 1.2 litres of the gas.


1mark www.freekcsepastpapers.comPage 102 3. A Crude oil is a mixture of several compounds which are separated in a refinery as shown below. I What is the name of the apparatus above 1mark ii What is the name of the process which is used in separation of crude oil 1mark iii What physical property of the compounds in the mixture does the separation depend on. 1mark iv Use the letter A to G to describe where the following could be formed: 1mark I The fraction that represent gases II The fraction that represents the largest molecules 1mark b The scheme below was used to prepare a cleansing agent. Study it and answer the questions that follow. I What name is given to the type of cleansing agent prepared by the method above 1mark ii Name the chemical substance added in step II 1mark iii What is the purpose of adding the chemical substance named above. 1mark c i Identify the following substances 1mark A C ii Name process I and II 1mark iii Draw the structure of the organic product formed when compound N reacts with methanol 1mark iv Explain how you would distinguish compound N and C 1mark 4. A i Sea water contains approximately 3 sodium chloride. Describe how sodium chloride is obtained from sea water 3marks ii The solubility of sodium chloride is 36.2g in 100g of water at 300c. Determine the concentration in moles per litre of a saturated aqueous sodium chloride at 300c. Na 23, Cl 35.5 density of water 1g cm3 2marks b Water containing hydrogen carbonate, HCO3-and calcium ions, Ca2 is said to be hard. Explain how these ions get into sources of water. 2marks www.freekcsepastpapers.comPage 103 c Analysis of river water sample showed the presence of the following ions: Mg2 , Na , Cl , 24SO i Name the type of water hardness present in the sample 1mark ii Identify two methods used to remove this type of hardness.


Na 23, Cl 35.5 density of water 1g cm3 2marks b Water containing hydrogen carbonate, HCO3-and calcium ions, Ca2 is said to be hard. Explain how these ions get into sources of water. 2marks www.freekcsepastpapers.comPage 103 c Analysis of river water sample showed the presence of the following ions: Mg2 , Na , Cl , 24SO i Name the type of water hardness present in the sample 1mark ii Identify two methods used to remove this type of hardness. 2marks d Study the information in the table below and answer the questions that follow. Salt Solubility in g 100g water At 400C At 600C Na NO3 38 24 Na Cl 101 52 A mixture containing 31g NaNO3 and 47g NaCl in 100g of water at 600c was cooled to 400c. A Which salt crystallizes out and by what mass 1mark b Identify the method used to obtain crystals 1mark 5. A The diagram below shows the Frasch process used for extraction of sulphur. Use it to answer the questions that follow. I Identify X 1mark ii Why is it necessary to use superheated water in this process? 1mark iii State two physical properties of sulphur that makes it possible for it to be extracted by this method 2marks b The diagram below shows part of the process in the manufacture of sulphuric VI acid. Study it and answer the questions that follow. I Write an equation for the reaction in the absorption chamber 1mark ii Explain how the acid is obtained after the reaction in the absorption chamber 1mark iii State two roles of the heat exchanger 2marks iv How is pollution controlled in the above process 1mark www.freekcsepastpapers.comPage 104 c Complete the table below to show the observation made and property when sulphur IV oxide is bubbled through the following. 3marks Substance Observation Property Acidified potassium Dichromate VI solution 1mark mark Moist hydrogen sulphide 1mark mark 6.


Study it and answer the questions that follow. I Write an equation for the reaction in the absorption chamber 1mark ii Explain how the acid is obtained after the reaction in the absorption chamber 1mark iii State two roles of the heat exchanger 2marks iv How is pollution controlled in the above process 1mark www.freekcsepastpapers.comPage 104 c Complete the table below to show the observation made and property when sulphur IV oxide is bubbled through the following. 3marks Substance Observation Property Acidified potassium Dichromate VI solution 1mark mark Moist hydrogen sulphide 1mark mark 6. A Use the following data to calculate the enthalpy change for the decomposition of calcium carbonate Ca s O2 g Ca O s H -635kJmol-1 Ca s C s 3 2O2 g Ca CO3 s H - 1207kJ mol C s O2 g CO2 g H -394kJ Mol 2marks b State two factors to consider when choosing a fuel 1mark c The diagram below represents a set up used to determine the molar heat of combustion of ethanol. Calculate: i Heat given out during the experiment density of water 1g cm3, C 4.2kJ kg k 2marks ii Molar heat of combustion C 12, O 16, H 1 2marks iii Write the thermochemical equation for the combustion of ethanol 1mark d i State Hess s law 1mark ii Study the information below and answer the questions that follow. MgCl2 s Mg2 g 2 Cl- g H 2487kJ mol.


A Use the following data to calculate the enthalpy change for the decomposition of calcium carbonate Ca s O2 g Ca O s H -635kJmol-1 Ca s C s 3 2O2 g Ca CO3 s H - 1207kJ mol C s O2 g CO2 g H -394kJ Mol 2marks b State two factors to consider when choosing a fuel 1mark c The diagram below represents a set up used to determine the molar heat of combustion of ethanol. Calculate: i Heat given out during the experiment density of water 1g cm3, C 4.2kJ kg k 2marks ii Molar heat of combustion C 12, O 16, H 1 2marks iii Write the thermochemical equation for the combustion of ethanol 1mark d i State Hess s law 1mark ii Study the information below and answer the questions that follow. MgCl2 s Mg2 g 2 Cl- g H 2487kJ mol. MgCl2 s aq Mg Cl2 aq H2 -170 kJ mol 2Cl- g aq 2Cl- aq H3 -762kJ mol a Name the enthalpies H1 and H2 1mark b Determine the enthalpy for the reaction 2marks Mg2 g aq Mg 2 aq 7. A Study the flow chart below and use it to answer the questions that follow.


MgCl2 s Mg2 g 2 Cl- g H 2487kJ mol. MgCl2 s aq Mg Cl2 aq H2 -170 kJ mol 2Cl- g aq 2Cl- aq H3 -762kJ mol a Name the enthalpies H1 and H2 1mark b Determine the enthalpy for the reaction 2marks Mg2 g aq Mg 2 aq 7. A Study the flow chart below and use it to answer the questions that follow. Results: Initial water temperature 22.00C Final water temperature 44.50C Mass of lamp before burning 126.5g Mass of lamp after burning 125.0gwww.freekcsepastpapers.comPage 105 I Name: R, S and T 3marks II Write the chemical equation for the reaction between i R and concentrated sulphuric VI acid 1mark ii T and hydrochloric acid 1mark III What is the role played by R in the reaction in II i above 1mark b Study the flow chart below and use it to answer the questions that follow.


MgCl2 s aq Mg Cl2 aq H2 -170 kJ mol 2Cl- g aq 2Cl- aq H3 -762kJ mol a Name the enthalpies H1 and H2 1mark b Determine the enthalpy for the reaction 2marks Mg2 g aq Mg 2 aq 7. A Study the flow chart below and use it to answer the questions that follow. Results: Initial water temperature 22.00C Final water temperature 44.50C Mass of lamp before burning 126.5g Mass of lamp after burning 125.0gwww.freekcsepastpapers.comPage 105 I Name: R, S and T 3marks II Write the chemical equation for the reaction between i R and concentrated sulphuric VI acid 1mark ii T and hydrochloric acid 1mark III What is the role played by R in the reaction in II i above 1mark b Study the flow chart below and use it to answer the questions that follow. I Write the formula of the metal ion in solution W 1mark ii Name the white precipitate Q 1 mark iii What property of the white precipitate is illustrated in step II and III 1mark iv Write the equation for the reaction taking place in step II 1mark www.freekcsepastpapers.comPage 106 CEKENAS PREMOCK EXAMINATION, 2023 Kenya Certificate of Secondary Education 233 3 CHEMISTRY PAPER 3 CONFIDENTIAL INSTRUCTIONS In addition to the laboratory facilities each student requires the following: About 50cm3 of solution P About 80cm3 of solution Q Two pieces of solid M A burette A pipette and pipette filler 50cm3 measuring cylinder Thermometer A stop watch A 250ml volumetric flask A 250ml empty beaker A 100ml plastic beaker One label 2 conical flasks Complete stand About 10cm3of liquid L in a stopped boiling tube.


A Study the flow chart below and use it to answer the questions that follow. Results: Initial water temperature 22.00C Final water temperature 44.50C Mass of lamp before burning 126.5g Mass of lamp after burning 125.0gwww.freekcsepastpapers.comPage 105 I Name: R, S and T 3marks II Write the chemical equation for the reaction between i R and concentrated sulphuric VI acid 1mark ii T and hydrochloric acid 1mark III What is the role played by R in the reaction in II i above 1mark b Study the flow chart below and use it to answer the questions that follow. I Write the formula of the metal ion in solution W 1mark ii Name the white precipitate Q 1 mark iii What property of the white precipitate is illustrated in step II and III 1mark iv Write the equation for the reaction taking place in step II 1mark www.freekcsepastpapers.comPage 106 CEKENAS PREMOCK EXAMINATION, 2023 Kenya Certificate of Secondary Education 233 3 CHEMISTRY PAPER 3 CONFIDENTIAL INSTRUCTIONS In addition to the laboratory facilities each student requires the following: About 50cm3 of solution P About 80cm3 of solution Q Two pieces of solid M A burette A pipette and pipette filler 50cm3 measuring cylinder Thermometer A stop watch A 250ml volumetric flask A 250ml empty beaker A 100ml plastic beaker One label 2 conical flasks Complete stand About 10cm3of liquid L in a stopped boiling tube. Six test tubes and a test tubes rack About 10cm3of solutions R in boiling tube Wooden splint Spatula Filter paper and filter funnel Access to Source of heat.


B ALL working MUST be clearly shown where necessary. C Mathematical table and silent electronic calculators may be used. 1. You are provided with: i Solution P which is a monobasic acid solution. Ii 2cm long magnesium ribbon labelled metal M. iii 0.5M sodium hydroxide solution Q You are required to: a Calculate the mass of the 2cm long metal M. b Determine the molarity of the dibasic acid solution P. PROCEDURE 1 Measure exactly 40cm3 of solution P using 50ml measuring cylinder and transfer it into a 100ml plastic beaker. Measure the temperature of the solution after every thirty seconds for the first sixty and record in table I below. At exactly 90 seconds add the 2cm long solid M and record the temperature of the solution after every thirty seconds up to 300 seconds RETAIN THIS SOLUTION FOR PROCEDURE II BELOW Table I Time sec 0 30 60 90 120 150 180 210 240 270 300 Temperature X 4marks a Draw a graph of temperature against time in the grid provided below. 3marks b From the graph determine the highest temperature change, T 1mark c Calculate the heat change for the reaction above in kJ 1mark Density of solution 1g cm3 specific Heat capacity of solution 4.2Jg-K-mol- d i Given that the molar enthalpy reaction between metal M and acid P is 1590kJmol , determine the number of moles of metals M in the 2cm long pieces. 1mark e Given that R.A.M of Magnesium is 24.1. Calculate the mass of the 2cm long ribbon 1mark PROCEDURE II Transfer all the solution formed from procedure I into a 250ml volumetric flask. Add distilled water to the mark, transfer the solution into a 250ml beaker and this solution as P1. Fill the burette with solution Q Pipette 25cm 3 of solutions P1 into a 250 ml conical flask. Titrate solution Q against P1 using phenolphthalein indicator and record your results in table II below. Repeat the titration two more times to get consider values.


The diagram below shows part of the Frasch process used for extraction of sulphur. Use it to answer the questions that follow. A Identify X 1mk b Why is it necessary to use superheated water and hot compressed air in this process? 1mk c State two physical properties of sulphur that makes it possible for it to be extracted by this method. 1mk 10. Hydrogen sulphide gas was bubbled through a solution of zinc nitrate for some time. I. State observation made. 1mk ii. Where should the experiment be carried out and why? 1mk iii. Write the equation of the reaction that occurs. 1mk 11. Calcium carbonate reacts with dilute sulphuric VI acid to form a gas and a salt. I. Write an equation for the above reaction. 1mk ii. Why would the above reactants not be suitable for preparation of the above gas in the laboratory? 2mks 12. A student prepared ammonia gas and bubbled it in a solution of copper II sulphite as shown below. A State the observation made in the beaker after; i. A short while 1 mk ii. A long while 1 mk b Write the formula of the ion formed in the beaker in a ii above. X Heat Mixture of NH4Cl and Ca OH 2 Beaker Copper II sulphate solution 15atm www.freekcsepastpapers.comPage 119 13. Study the table below and answer the question that follow. Solution pH A 3.0 B 14.0 C 8.0 i. In which solution will phenolphthalein indicator be colourless? Explain 1mk ii. Which of the solutions can be used to relieve a heartburn. Explain 1mk iii. Which two solutions can react with zinc oxide. 1 mk 14. The diagram below shows a set up that was used to show the part of air used in burning. A Given that phosphorous was in excess, draw a diagram of the set up at the end of the experiment when there was no further observable change. 1 mk b Suggest of one modification that can be made to the apparatus if the percentage of air used is to be determined.


How will increase in pressure affect the yield of nitrogen II oxide? 1mk 20. After 7.5 hrs the percentage of a certain nuclide in a sample of ore was found to be 12.5 . A What is meant by the term half-life? 1mk b Determine the half-life of the nuclide. 2mks 21. Name the following compound. Ii. CH3 COOCH2CH2CH3 1 mk b Complete the equation below. 1mk Inverted gas jar A piece of burning phosphorous Waterwww.freekcsepastpapers.comPage 120 22. The diagram below represented a set up that was used to react Lithium with water. Study it and answer the question that follow. A Complete the diagram to show how the gas formed can be collected. 1mk b Write an equation for the reaction that takes place. 1mk c Why would it not be advisable to use potassium in place of lithium in the above set up. 1mk 23. During extraction of aluminium. Aluminium oxide with melting point of 20540C is electrolysed but the temperature is maintained between 8000C and 9000C. a Explain why electrolysis is not carried at 20540C 1mk b How can the temperature be lowered from 20540C to about 8000C 1mk c State one use of aluminium. 1 mk 24. The scheme below represents reactions starting with solid X. i. Identify solid X. 1mk ii. Write an ionic equation to show formation of white precipitate. 1 mk iii. Why would gas S not form a white precipitate with solution of sodium hydroxide. 25. The electrode potentials for elements C and D are given below. C 2 aq 2 e- C s E - 0.38V D 2 aq 2 e- D s E -0.67V Is it advisable to store a nitrate solution of C in a container made of element D? Explain showing your working. 3 mks 26. A Water is polar. What is meant by the term polar?


Name the catalyst Y. 1mk II. State one commercial use of sulphuric VI acid. 1mk d i. The copper obtained from the chamber N is not pure. Draw a labelled diagram to show the set up you would use to refine the copper by electrolysis. 2mks ii. Given that the mass of copper obtained from the above extraction was 210kg. Determine the percentage purity of the ore copper pyrites if 810kg of it was fed to the 1st roasting furnace. Cu 63.5, Fe 56, D 32 3mks 4. Use the standard electrode potentials given below to answer the questions that follow. A Select two half cells which when connected give the lowest electromotive force e.m.f 1mk b Calculate the e.m.f of the cell formed by combining the half cells in a above. 1mk c Select the; i. Strongest oxidizing agent. 1 2 mk ii. Strongest reducing agent 1 2 mk d A cell was set up using lead and zinc electrodes as shown below. I. Write the half cell equation for the half cell in which oxidation takes place. 1 mk ii. Write the overall cell equation. 1mk iii. What is the role of the salt bridge? 2mks e An iron knife was electroplated using chromium. The knife was thoroughly cleaned and weighed before being dipped in the electrolyte used. I. Why is it necessary to clean the knife before electrolysis is carried out. 1mk ii. A current of 0.75A was passed through the electrolyte for one hour and 4 minutes. The mass of chromium deposited on the knife was 0.52g. Determine the valency of chromium. 1F 96500C, Cr 52 2mks 5. The sketch below represents a graph obtained when zinc granules were reacted with excess 0.2M sulphuric acid in the presence of a catalyst in a conical flask placed on an electronic balance. Www.freekcsepastpapers.comPage 124 a i Write an equation for the reaction that took place. 1mk ii. Explain why there is loss in mass.


Www.freekcsepastpapers.comPage 124 a i Write an equation for the reaction that took place. 1mk ii. Explain why there is loss in mass. 1mk b Sketch on the same axes, the curve obtained when: I: Same mass of zinc powder was used under the same conditions. Label it P. 1mk II: No catalyst was used. Label it N. 1 mk c In the contact process, sulphur IV oxide is converted to sulphur VI oxide in the catalytic chamber in which a dynamic equilibrium is reached. 2 SO2 aq O 2 g 2SO 2 g H -97kJ Mol i. What is meant by dynamic equilibrium? 2mks ii. State and explain how each of the following would affect the position of the equilibrium. I. Decrease in pressure. 2mks II. Decrease in temperature. 2mks d An equilibrium exists between chromate and dichromate ions as shown below. 2CrO4 2- aq 2H Cr2O7 2- aq H2O l yellow aq Orange State and explain the observation made when aqueous sodium hydroxide is added to the above mixture. 2mks 6. A The table below shows properties of chlorine, bromine and iodine. Complete the table by giving the missing information in i , ii and iii 3mks b Chlorine gas is prepared by reacting concentrated hydrochloric acid with manganese IV oxide. I. Write the equation for reaction between concentrated hydrochloric acid and manganese IV oxide. 1mk ii. What is the role of manganese IV oxide in this reaction. 1mk c i. Iron II chloride reacts with chlorine gas to form substance E. Identify substance E. 1mk ii. During the reaction in c i above, 6.30g of iron II chloride were converted to substance E. Calculate the volume of chlorine used.


1mk ii. During the reaction in c i above, 6.30g of iron II chloride were converted to substance E. Calculate the volume of chlorine used. 3mks Cl 35.5, Molar gas volume at room temperature 24000cm3, Fe 56 d Draw and name the structure of the compound formed when excess chlorine gas is reacted with ethane gas. 2mks e Give two industrial uses of chlorine. 2mks 7. In an experiment 50cm3 of 1.0M sodium hydroxide solution was placed in a suitable apparatus and 5.0cm3 portion of hydroxide acid were added. The resulting mixture was stirred with a thermometer and temperature recorded after each addition. Volume of HCl cm3 5 10 15 20 25 30 35 40 45 50 Temperature 0C 21.5 22.5 24.0 25.0 26.0 27.0 27.5 27.5 27.0 26.5 a Plot a graph of temperature against volume of the acid added. 3mks b i. From the graph determine volume of HCl used to neutralize 50cm3 of 1M NaOH. 1mk ii. Hence determine concentration of the HCl in moles per litre. 3mks c i. Calculate the amount of heat produced in the reaction Specific heat capacity 4.2 kjKg-1 k-1 and density of the solution 1g cm3 2 mks ii. Hence calculate the molar enthalpy of neutralization of sodium hydroxide. 1mk www.freekcsepastpapers.comPage 125 KIRINYAGA CENTRAL EFFECTIVE 40 JOINT EXAMINATION, 2023 233 3 CHEMISTRY PAPER 3 CONFIDENTIAL Each candidate should have the following :- 1. 90cm3 of solution X. 2. 100cm3 of solution Y. 3. 120cm3 of solution Z. 4. 6 test tubes in a rack and 1 boiling tube. 5. 50ml measuring cylinder. 6. A conical flask. 7. A burette. 8. A 25ml pipette. 9.


8. A 25ml pipette. 9. A thermometer -100C 1100C 10. Stopwatch. 11. About 15cm3 of liquid Q. 12. Watch glass. 13. Test tube holder. 14. 0.1g NaHCO3. 15. A dropper. 16. 1g ammonium iron II sulphate hexahydrate. Labelled solid T NH4 2 SO4FeSO4.6H2O 17. 500cm3 distilled water in a wash bottle. 18. Metallic spatula. 19. One blue litmus paper and one red litmus paper. Access to:- 1. 2M NaOH with own dropper. 2. 0.1M acidified potassium dichromate VI with a dropper. 3. 0.2Macidified barium nitrate with own dropper. 4. 20 hydrogen peroxide with own dropper. 5. 2M NH4OH with own dropper. 6. 0.02M acidified potassium manganate VII with a dropper. 7. Bunsen burner flame. Solution preparation confidential. 1. Solution X- Ferrous Ammonium sulphate. Prepared by dissolving 34g of Ferrous Ammonium Sulphate in 1000cm3 of distilled water. Note that this solution should be prepared the morning of the exam and also per shift to prevent oxidation. 2. Solution Y Acidified potassium manganate VII . Prepared by dissolving 3g of potassium Manganate vii crystals in 800cm3 of distilled water then adding 200cm3 of 2M sulphuric VI acid. 3. Solution Z Oxalic acid. Prepared by dissolving 6.3g of oxalic acid in 1000cm3 of water. 4. Acidified potassium dichromate VI is prepared by dissolving 29.4g in 200cm3 2M sulphuric VI acid and top up to 1litre using distilled water. 5. Acidified barium nitrate is prepared by dissolving 52.3g of barium nitrate in 200cm3 of HNO3 and top up the solution with distilled water to 1l 1000cm3 6. Liquid Q is ethanol.


1 mk b Given that the equation for the reaction between solution Y and X is: MnO- 4 aq 8H aq 5Fe 2 aq Mn2 aq 5Fe3 aq 4H2O l Determine i. The number of moles of iron II salt, solution X in 25cm3 of the solution used. 1 mk ii. The concentration of solution X in moles per litre. 1 mk iii. The relative formula mass of the iron II salt. 1mk iv. The value of n in the formula FeSO4 NH4 2SO4.nH2O. 1mk Fe 56, N 14, S 32, O 16, H 1 Procedure 2 Using a burette place 1 cm3 of solution Y in each of the 5 test tubes on the rack. Measure 20cm3 of solution Z into a boiling tube using a measuring cylinder. Put a thermometer into solution Z in the boiling tube and warm it until it attains a temperature of 400C. Place the boiling tube in the rack and add the first portion of solution Y in the test tube and immediately start the start watch. Record the time taken for the purple colour to be decolourised in the table 2 below. Repeat the procedure above with 20cm3 solution Z at 500C, 600C, 700C and 800C to fill table 2. Clean the test tubes and the burette immediately you finish the experiment. Table 2 4 mks Temperature of solution Z 0C 40 50 60 70 80 Time taken for colour to decolourise sec t Rate 1 t sec-1 a On the grid below, plot a graph of rate l t against temperature 0C . 3mks b From the graph, determine the time for decolourisation of the mixture if temperature of solution was 580C. 1mk c Explain how the rate of reaction between solution Y and solution Z varies with change in temperature. 2mks www.freekcsepastpapers.comPage 127 2. You are provided with organic liquid Q.


Give one reason why they have low melting points. 1 mark 3. A heavy metal P was dissolved in dilute nitric acid to form a solution of compound P NO3 2. Portions of the resulting solution were treated as follows: i To the first portion a solution of dilute hydrochloric acid is added, where a white precipitate S is formed, which dissolves on warming. Ii The second portion is treated with two drops of 2M Sodium hydroxide solution where a white precipitate T is formed. The white precipitate dissolved in excess sodium hydroxide to form a colourless solution. Iii A solution of potassium iodide is added to the third portion where a yellow precipitate U is formed. Iv When the resulting solution is evaporated to dryness and heated strongly a yellow solid V is formed and a brown gas W and a colourless gas X are formed. A. Identify the substances P, S, T, U, V, W 3 marks b. Write an ionic equation of the reaction that occurs in part iii 1 mark A B C Fwww.freekcsepastpapers.comPage 137 4. 100cm3 of air is continuously passed through a combustion tube connected to two syringes as shown below. The combustion tube contains some clean granules of copper metal which are heated. The process is repeated until there is no further change in the volume of air. The volume of air remaining is 80cm3 i State one observation made in the combustion tube 1mark ii Work out the percentage of air used after the reaction 1mark iii List two gases remaining after the reaction 1 mark iv Would the reaction take place if it is repeated with magnesium in place of copper metal explain 1mk 5. The electronic configuration of the ions of X3 and Y are 2, 8 and 2, 8 respectively. I . Write the electronic configuration of the neutral atoms of X and Y 1 mark ii . Write the formula of the compound formed between element X and O 1 mark iii . Compare the atomic radius of element X and Y 2 marks 6. The diagram below represents an experiment which was carried out by a student, to investigate the effect of passing an electric current on molten sodium chloride. I . Molten sodium chloride is a binary electrolyte.


The diagram below represents an experiment which was carried out by a student, to investigate the effect of passing an electric current on molten sodium chloride. I . Molten sodium chloride is a binary electrolyte. State the meaning of the term binary electrolyte. 1 mark ii . State two observations made at the anode 1 mark iii . Write an equation to show what happens at the cathode. 1 mark iv Show the direction of flow of electrons on the set up mark 7. 100cm3 of propane gas diffuses through a porous plug in 20 seconds. How long would it take for 80cm3 of methane gas to diffuse through the same plug? C 12, H 1 3marks Combustion tubeSyringe AHeated Copper MetalSyringe BGraphite electrodeBeakerMolten Sodium Chloridewww.freekcsepastpapers.comPage 138 8. The graphs below were drawn when 15g of marble chips in different physical states were reacted with 50cm3 of 2M Hydrochloric acid. They are drawn by measuring the volume of carbon iv oxide produced with time. A Which curves corresponds to the reactions involving powdered calcium carbonate and large sized marble chips with the dilute acid. I Powdered calcium carbonate 1 mark ii Large sized calcium carbonate 1 mark b All the graphs eventually flatten out at the same level but at different time. Why do the graphs flatten out at the same level? 1 mark c Why is curve A very steep at any given point compared to the other curves 1 mark 9. One mole of ethane gas was mixed with excess chlorine gas in a gas jar at room temperature and kept in dark conditions. On observation, no reaction occurred in the dark conditions. On exposure to light the chlorine gas was decolourised. A State the importance of light in the above reaction. 1 mark b Write an equation for the reaction that occurs once the mixture is exposed to light.1mark c Name the organic product formed in the above reaction 1mark 10. Below is an equation showing an equilibrium Br2 aq H2O l Br aq 2H aq OBr aq State and explain the observation that would be made if some drops of concentrated sodium hydroxide solution were introduced to the equilibrium mixture 3 marks 11.


A State the importance of light in the above reaction. 1 mark b Write an equation for the reaction that occurs once the mixture is exposed to light.1mark c Name the organic product formed in the above reaction 1mark 10. Below is an equation showing an equilibrium Br2 aq H2O l Br aq 2H aq OBr aq State and explain the observation that would be made if some drops of concentrated sodium hydroxide solution were introduced to the equilibrium mixture 3 marks 11. A mixture of dilute nitric acid 50 water 50 acid was reacted with copper turnings in a round bottomed flask. I Name the gas that is produced in the above case. 1 mark ii Write a balanced equation to show the reaction 1 mark iii State two physical properties of the gas evolved above. 1 mark 12. The molar enthalpy of combustion of propanol is 1560Kjmol 1 i Write an equation to show the combustion of ethanol completely in oxygen 1 mark ii Calculate the amount of energy in joules released when10g of propanol is burnt in excess oxygen 2 marks iii The practically obtained value of enthalpy of combustion of propanol is less than the value obtained from books. Give two reasons for the above variation. 1 mark 13. Given a solid sample of calcium carbonate and sodium chloride, explain how you can obtain some pure crystals of sodium chloride. 3 marks Volume of Co 4050Curve ACurve BCurve CTime4050www.freekcsepastpapers.comPage 139 14 The solubility curves below shows the solubility of two salts A and B in water. Study it and answer the questions that follow: i Which salt is more soluble in water at 70oc 1mark ii Work out the amount of salt that would saturate 50gm of water at 120sc 2mark 15. 3.78g of a hydrated salt of iron II sulphate, FeSO4, in H2O were heated until all the water of crystallization was driven off. The anhydrous salt left had a mass of 1.52g. Determine the formula of the hydrated salt.


3.78g of a hydrated salt of iron II sulphate, FeSO4, in H2O were heated until all the water of crystallization was driven off. The anhydrous salt left had a mass of 1.52g. Determine the formula of the hydrated salt. Fe 56, S 32, H 1, O 16 3 marks 16. A steady current of 0.2 Amperes was passed through molten silver bromide for 80 minutes. I . Calculate the quantity of electricity that passed through the set up. 1 mark ii . Calculate the mass of product deposited at the cathode. 1F 96500C; Ag 108, Br 80 2 marks 17. The apparatus set up below was used to prepare an anhydrous solid P i Identify solid P 1 mark ii Write an equation for formation of solid P 1 mark iii Suppose the gas used in the set up was dry hydrogen chloride gas; what would be the product obtained after the reaction? Give a reason for your answer 1020 40 60 80 100 120 140Salt ASalt BSolubility g per 100g of H o2Temp C 0DryChlorine gasDrying agent MIron wireSolid Pwww.freekcsepastpapers.comPage 140 18. A radioactive cobalt Co6128 undergoes decay by emitting a beta particle and forming Nickel atom, a Write a balanced decay equation for the above change 1 mark b If a sample of the cobalt has an activity of 1000 counts per minute, determine the time it would take for its activity to decrease to 62.50 if the half-life of the element is 30years 2 marks c Define the term half-life. 1 mark 19.


Give a reason for your answer 1020 40 60 80 100 120 140Salt ASalt BSolubility g per 100g of H o2Temp C 0DryChlorine gasDrying agent MIron wireSolid Pwww.freekcsepastpapers.comPage 140 18. A radioactive cobalt Co6128 undergoes decay by emitting a beta particle and forming Nickel atom, a Write a balanced decay equation for the above change 1 mark b If a sample of the cobalt has an activity of 1000 counts per minute, determine the time it would take for its activity to decrease to 62.50 if the half-life of the element is 30years 2 marks c Define the term half-life. 1 mark 19. The table below gives the solubility of potassium bromide and potassium sulphate at 0oc and 40oC Substance Solubility g 100g H2O at 0oc 40oC Potassium bromide 55 75 Potassium sulphate 10 12 When an aqueous mixture containing 60g of potassium bromide and 7g potassium sulphate in 100g of water at 80oc was cooled to 0oC, some crystals were formed a Identify the crystals 1mark b Determine the mass of the crystals 1mark c Name the method used to obtain the crystals 1mark 20. The table below gives some information about the melting and the likely structures in substances V, W, and X. Complete the table by filling the missing Information in the spaces numbered. I, II and III 3marks Element Structure Example Melting point V Grant Metallic i High W ii F2 Low X iii Si Very high 21. Use for diagram below to answer the questions that follows:- a Name the letter that corresponds to: i Activation energy of the reaction 1mark ii Change in energy for the overall reaction. 1mark b The reaction exothermic or endothermic. Explain. 2mark www.freekcsepastpapers.comPage 141 22. Study the set up below and answer the question that follows a Write an equation for the reaction which takes place in the combustion tube.


Explain. 2mark www.freekcsepastpapers.comPage 141 22. Study the set up below and answer the question that follows a Write an equation for the reaction which takes place in the combustion tube. 1mark b What property of gas Z to allows it to be collected as shown in the diagram . 1mark c Identify gas Z 1mark 23. The setup below was used to prepare dry sample or hydrogen sulphide gas. A Complete the diagram to show how the gas was collected. 1mark b Identify the following solids; H J 2marks 24. The table below shows the atomic and ionic radius of some elements. Element Atomic Radius nm Ionic radius nm U V W X 0.174 0.203 0.099 0.136 0.099 0.133 0.181 0.065 a Classify X as a metal or non-metal. Explain 1mark b Identify the element which is the strongest reducing agent. 1mark c Which element forms an anion? 1mark www.freekcsepastpapers.comPage 142 WEITHAGA JOINT MOCK EXAMINATIONS, 2023 Kenya Certificate of Secondary Education 233 2 Chemistry PAPER 2 Theory TIME: 2 HOURS 1. I The table below shows properties of some elements represented by symbols W, X, Y and Z. Study the information in the table and answer the questions that follows Element No. Of protons Atomic radius nm Boiling point 0C W 2 0.93 -269 X 10 1.31 -246 Y 18 1.54 -186 Z 36 1.89 -152 a Write down the electron arrangement for elements W and X 1mk b In which group of the periodic table are the elements in the table above? Give the name of the group 2mks c Explain why the atomic radius of W is smaller than that of X 1mk d state one use of element X 1mk II. The section below represents part of the periodic table. Study it and answer the questions that follow. The letters are not the actual symbol of the elements. Q X B H M T Y A V Z S a Select the least reactive non-metal.


Study it and answer the questions that follow. The letters are not the actual symbol of the elements. Q X B H M T Y A V Z S a Select the least reactive non-metal. 1mk b Which of the elements has the greatest tendency of forming covalent compounds in nature? Explain your choice. 1mk c Explain why the atomic radius of T is smaller than that of M. 2mks d Compare the electrical conductivity of element X and B. 2mks 2. Two half cells were connected as shown to form a voltaic cell. The reduction potentials are given. Pb2 aq 2e Pb s E 0.13V Fe2 aq 2e Fe s E 0.44V a Calculate the e.m.f of the cell. 1mk b Sodium chloride is used as the salt bridge. State the two functions of the salt bridge. 2mks c Show the direction of the electron flow in the external circuit. 1mk d The e.m.f of the cell will reduce with time. Give a reason for this. 1mk www.freekcsepastpapers.comPage 143 e During electrolysis of water acidified with Sulphuric acid, two gases were produced at the electrodes: i State which ions are preferentially discharged at the electrodes. Explain with aid of half ionic equations. Anode. 1mk Cathode. 1mks ii Calculate the volume of the gases at s.t.p produced when a current of 0.025A is passed for 4 hours. 1 Faraday 96500C 3mks 3. A The fermentation of glucose is catalysed by enzymes from yeast. Yeast is added to aqueous glucose, the solution starts to bubble and becomes cloudy as more yeast cells are formed. C6H12O6 aq 2C2H5OH aq 2CO2 g The reaction is exothermic. Eventually the fermentation stops when the concentration of ethanol is about 12 . I On a large scale, the reaction mixture is cooled. Suggest a reason why this is necessary. 1mk ii Why does the fermentation stop? Suggest one reasons.


An experiment was carried out using magnesium ribbon and dilute hydrochloric acid of different concentrations. The time needed to produce 50cm3 of the gas for every experiment was recorded in a table. Concentration of HCl moles per litre 2.0 1.75 1.50 1.25 1.00 0.75 0.50 0.25 Time seconds 8.8 10.0 11.7 14.0 17.5 18.7 35.0 70.0 time1 Sec-1 a Complete the table above for 1 time. 4mks b Plot a graph of rate i.e 1 time against concentration. 3mks www.freekcsepastpapers.comPage 144 c From your graph determine the concentration needed to produce 50cm3 of hydrogen gas when time is 15.0 seconds 1mk d From your graph state the relationship between the rate of reaction and concentration. Give a reason. 1mk e A state of equilibrium between dichromate vi and chromate ions is established as shown below Cr2O72- aq 2OH- aq 2CrO42- aq H2O l Orange Yellow i What is meant by dynamic equilibrium? 1mk ii State and explain observation made, when a few drops of Hydrochloric acid are added to equilibrium mixture 2mks 5. A Read the following passage and answer the questions. A salt K was heated with slaked lime calcium hydroxide . A colourless gas L with a characteristic smell and turns red litmus paper blue was evolved. A large quantity of this gas was passed through an inverted filter funnel into Copper II sulphate solution, and a deep blue solution M was obtained. I Identify gas L 1mk ii What is K most likely to be? 1mk iii Write an equation for the reaction between K and slaked lime 1mk iv .


1mk ii What is the identity of metal F. 1mk iii State the name of the ore from which metal F is extracted. 1mk iv Explain why the metal loses its lustre when exposed to air. 1mk v What is the function of wire gauze shell that separates the anode from the cathode? 1mk vi Write a chemical equation for the reaction between metal F and ammonia 1mk vii Apart from being a deoxidizing agent, state two other uses of metal F. 1mks b During extraction of aluminium by electrolysis, molten cryolite is used instead of water and the anode must be replaced from time to time. I State the main ore from which aluminium is extracted 1mk ii Explain why cryolite is preferred over water 1mk iii Give a reason why the anode is replaced from time to time. 1mk iv Extraction of aluminium is very expensive compared to other metals like Iron, explain 1mk 8. A Consider the following reaction: A2 g B2 g 2AB g , H 75 kJ Sketch an energy level diagram showing the relative activation energies for the catalysed and uncatalysed reactions using the axes below. 2mks b The following data was obtained during an experiment Mass of ethanol burnt 0.2g Mass of water in the calorimeter 200g Specific heat capacity of water 4.2 jg-1k-1 Initial temperature of water 23.5 0C Final temperature of water 28.0 0C i How was the mass of ethanol that burnt determined? 1mk ii How much heat was required to raise the temperature of water from 23.5 0C to 28.00C? 2mks iii Two assumptions were made in calculating the enthalpy of combustion for ethanol. State them. 1mk iv Determine the molar enthalpy of combustion of ethanol. C 12,H 1,O 16 2mks v Write a thermochemical equation for the combustion of ethanol given the accurate value for enthalpy of combustion is 1368 kJmol-1.


11. 400cm2 of distilled water. 12. Means of labeling. 13. About 0.5g of NaHCO3 Solid A. 14. 5cm3 of solution D. 15. About 1g of solid R. 16. Bunsen burner. Access to: 2M aqueous ammonia solution supplied with a dropper. Phenolphthalein indicator supplied with a dropper. 0.5M KI solution. 2M HCL 2M NaOH Zinc granules. 0.5 g Acidified KMnO4 supplied with a dropper. Acidified K2Cr2O7 supplied with a dropper. Solution D is a mixture of Pb NO3 2 and Cu NO3 2 ratio 1:1 Solid R is a maleic acid. Www.freekcsepastpapers.comPage 164 MURANG A EXTRA COUNTY SCHOOLS EXAMINATION. Kenya Certificate of Secondary Education 233 1 Chemistry Paper 1 Theory TIME: 2 HOURS 1 a Bauxite is the chief ore found in the extraction of Aluminium. Name two impurities found in bauxite 2mks b Name the chief ores of both zinc and copper 1mk i zinc ii copper 2. A Identify the products formed when dinitrogen tetra oxide is dissolved in water 2mks b Write the balanced equation for the reaction above 1mk 3. State one use of the following substances 3mks i AgBr ii CaSO4.XH2O iii Tincture of iodine 4. The grid below represents part of the periodic table. Study it and answer the questions that follow .The letters given do not represent the actual symbols of the elements. A B C D E F G H i Select the element that can form a divalent anion mk . Ii Name type of structure would the oxide of C have? Mk . Iii How does the melting point of A compare with that of E? Mk .


Mk . Iii How does the melting point of A compare with that of E? Mk . Iv 2.6 g of B reacts completely when heated with 2.42 litres of chlorine gas Cl2 at s.t.p, calculate the relative atomic mass of B. 1 mole of gas occupies 22.4 litres at s.t.p. 112mk . 5. Explain the differences in bleaching properties of chlorine and sulphur use equations where necessary 3mks 6. Metals K and N were connected to form a cell as shown in the diagram below. Their reduction potentials are as shown below: K aq K s - 0.17V N aq N s 1.1 6Vwww.freekcsepastpapers.comPage 165 i P is made by dipping a filter paper in a solution of sodium nitrate, on the salt bridge show the direction of flow of ions 1mk ii On the diagram, show the flow of electrons 1mk iii Write the equation for the half-cell reaction that occurs at 1mk Metal K electrode........................................................................... Metal N electrode........................................................................... 7. Write equations for the reactions between the following metals and steam. 3mks Iron Zinc Copper 8. Study the diagram below and answer the questions that follow. A. Name 1mk i Solid V ....... ii Gas W b. Describe a chemical test for chloride ions 2mks 9. Starting with ethanol, describe how a sample of tetrachloroethane can be prepared 3mks 10. A solution of bromine in water is a chemical reaction in equilibrium. The reaction involved is represented by the equation below; Br2 aq H2O l 2H aq Br- aq OBr- aq Yellow Colourless i State and explain the observation made when dilute sulphuric VI acid is added to the mixture at equilibrium. 2mks ii Define the term dynamic equilibrium 1mk 11.


A solution of bromine in water is a chemical reaction in equilibrium. The reaction involved is represented by the equation below; Br2 aq H2O l 2H aq Br- aq OBr- aq Yellow Colourless i State and explain the observation made when dilute sulphuric VI acid is added to the mixture at equilibrium. 2mks ii Define the term dynamic equilibrium 1mk 11. Apart from downward delivery name another method that can be used to collect the following gases 2mks i Nitrogen IV oxide Sulphur VI oxide ii Name one gas that can be dried using anhydrous calcium oxide 1mk 12. Starting with magnesium metal describe how a sample of magnesium carbonate can be prepared. 3mks 13. With aid of well labelled diagrams show how a sample of sodium chloride, iodine and sand can be separated 3mks 14. Explain the following 3mks i Why number of protons and electrons are equal in an atom ii The role of neutrons in the nucleus of an atom iii Cations are positively charged 15. A In an experiment 10.6g of a mixture of a anhydrous Sodium Carbonate and Sodium chloride were dissolved in water to make 100cm3 of solution .25cm3of this solution required 20cm3 of 1M Hydrochloric acid solution for complete neutralization. I Calculate the number of moles of Hydrochloric acid used 1mk ii Write a balanced equation for the above reaction. 1mk iii Calculate the mass of Sodium Carbonate in 25 cm3 of this mixture. 1mk 16. Briefly describe how caffeine can be extracted from tea leaves. 3mks 17. State the two roles of platinized-platinum in a standard hydrogen electrode 2mks 18.


Briefly describe how caffeine can be extracted from tea leaves. 3mks 17. State the two roles of platinized-platinum in a standard hydrogen electrode 2mks 18. Explain the following 3mks i Yellow phosphorus is stored under water ii Sodium is stored under paraffin oil iii Lime water and not potassium hydroxide is used to test for carbon iv oxide Solution of a sodium salt Solid V Gas W which turns K2Cr2O7 paper from orange to green BaCl2 aq HCl aq www.freekcsepastpapers.comPage 166 18. Study the information below and use it to answer the questions that follow H lattice MgCl2 - 2477kjmol-1 H hydration Cl-1 aq -363kjmol-1 H hydration Mg 2 aq -1891jmol-1 i Differentiate between hydration energy and lattice energy? 1mks ii Calculate the heat of solution of Magnesium Chloride 2mks 19. Nylon 6,6 is formed from two monomers, hexan-1,6-dioic acid adipic acid and hexan-1,6-diamine hexamethylene diamine through condensation polymerisation as shown in the diagrams below. A. Define condensation polymerisation 1mk b. Write the equation for the formation of Nylon 6,6 2mks 20. According to Bronsted-Lowry theory, define an acid 1mk NH3 aq H2O l NH4 aq OH- aq Identify the species that acts as; i A base. Explain . 1mks ii An acid. . Explain .. 1mk 21. A Explain how painting prevents iron from rusting 1mk b. Apart from protection from rusting state another reason for electroplating 1mk c. What is sacrificial protection, use an example to explain your answer. 2mks 22. The structure of RCOO-Na below represents a type of cleansing agent. Describe how the cleansing agent removes grease from a piece of cloth. 3mks 23.


The structure of RCOO-Na below represents a type of cleansing agent. Describe how the cleansing agent removes grease from a piece of cloth. 3mks 23. The diagram below represents a jiko when in use. Study it and answer the questions that follow. I Write equations for the reactions that occur in region I: B 1 mk II: C 1 mk ii Explain what happens in region A. 1 mks 24. A compound contains 82.75 carbon and the rest is Hydrogen. C 12, H 1 a Determine its empirical formula. 2 Mrks b Determine the molecular formula if its molecular mass is 58. 1 Mks 25. Determine the oxidation state of manganese in the following; 3mks KMnO4 Mn2O3 26. Explain why the melting point of magnesium oxide is 3080 C while that of carbon IV oxide is -79oC. 2mks Region A Region B Region C Air inwww.freekcsepastpapers.comPage 167 MURANG A EXTRA COUNTY SCHOOLS EXAMINATION. Kenya Certificate of Secondary Education 233 2 Chemistry PAPER 2 Theory TIME: 2 HOURS 1. A The graph below represents the trend in melting points of elements in period 3. Study it and use it to answer the questions that follow i Explain the trend in melting point between Aluminum and Phosphorous. 2 marks ii Give a reason why Argon has the lowest melting point 1 mark b The table below shows the properties of several elements. Study it and use it to answer the questions that follow. Element Atomic radius nm Ionic radius nm P 0.136 0.065 Q 0.174 0.099 R 0.099 0.181 S 0.203 0.133 i Giving a reason, identify the nonmetal 2 marks ii Given that, element P and S belong to the same period of the periodic table, identify the element with a lower ionization energy. Explain. 2 marks c An element X forms an ion with the formula X2 . The electronic configuration of the ion is 2.8 i State the group and period to which element X belongs.


Explain. 2 marks c An element X forms an ion with the formula X2 . The electronic configuration of the ion is 2.8 i State the group and period to which element X belongs. 1mark Group .. . Period ii Draw dot and cross diagram showing bonding when X combines with chlorine 1 mark d Explain the following observations; i Carbon has more than one melting point 1 mark ii Silicon and phosphorous are in the same period but at room temperature, the oxide of silicon is a solid, while the oxide of sulphur is gaseous 1 mark 2. A Determine the oxidation state of the element indicated in brackets 3 marks i. MnO4 Mn ii. K2 Cr2 O7 Cr iii. H3PO4 P www.freekcsepastpapers.comPage 168 b Below is a list of standard reduction potentials of some elements. Use it to answer the questions that follow. A 2 aq 2e A s 0.34 V N 2 aq 2e N s 0.76 V G aq 2e G s 0.00 V Y 2 aq 2e Y s 0.88 V L 2 aq 2e L s 2.16 V i Identify the strongest reducing agent 1 mark ii Explain why a solution containing A2 ions cannot be stored in a container made of metal N 1 mark iii The half cells of Y and L were combined to form an electrochemical cell. I Draw a well labelled diagram of the cell formed 3 marks II Calculate the e.m.f of the cell formed above 1 mark c The diagram below shows the set up used to investigate electrolysis of dilute sulphuric VI acid solution i Identify product X and Y 1 mark ii Write an equation for the reaction at the anode 1 mark iii Explain what happens to the solution after 2 hrs sometime 1 mark 3. Study the diagram below and use it to answer the questions that follow a.


A 2 aq 2e A s 0.34 V N 2 aq 2e N s 0.76 V G aq 2e G s 0.00 V Y 2 aq 2e Y s 0.88 V L 2 aq 2e L s 2.16 V i Identify the strongest reducing agent 1 mark ii Explain why a solution containing A2 ions cannot be stored in a container made of metal N 1 mark iii The half cells of Y and L were combined to form an electrochemical cell. I Draw a well labelled diagram of the cell formed 3 marks II Calculate the e.m.f of the cell formed above 1 mark c The diagram below shows the set up used to investigate electrolysis of dilute sulphuric VI acid solution i Identify product X and Y 1 mark ii Write an equation for the reaction at the anode 1 mark iii Explain what happens to the solution after 2 hrs sometime 1 mark 3. Study the diagram below and use it to answer the questions that follow a. During the experiment, the following data was collected Volume of water 400 cm3 Initial temperature of water 23.00 C Final temperature of water 35.00 C Initial mass of lamp and ethanol 99.07 g Final mass of lamp and ethanol 98.23 g Specific heat capacity 4.2 kJ Kg-1 K- Calculate the; i Temperature change 1 mark ii Heat change for the reaction 2 marks iii Mass of ethanol that reacted 1 mark iv Molar enthalpy of combustion of ethanol C 12, H 1.0, O 16.0 2 marks www.freekcsepastpapers.comPage 169 b.


I Draw a well labelled diagram of the cell formed 3 marks II Calculate the e.m.f of the cell formed above 1 mark c The diagram below shows the set up used to investigate electrolysis of dilute sulphuric VI acid solution i Identify product X and Y 1 mark ii Write an equation for the reaction at the anode 1 mark iii Explain what happens to the solution after 2 hrs sometime 1 mark 3. Study the diagram below and use it to answer the questions that follow a. During the experiment, the following data was collected Volume of water 400 cm3 Initial temperature of water 23.00 C Final temperature of water 35.00 C Initial mass of lamp and ethanol 99.07 g Final mass of lamp and ethanol 98.23 g Specific heat capacity 4.2 kJ Kg-1 K- Calculate the; i Temperature change 1 mark ii Heat change for the reaction 2 marks iii Mass of ethanol that reacted 1 mark iv Molar enthalpy of combustion of ethanol C 12, H 1.0, O 16.0 2 marks www.freekcsepastpapers.comPage 169 b. Use the information in the table below to answer the questions that follow Na g Cl- g NaCl s H1 776 kJ Mol Na g aq Na aq H2 390 kJ Mol Cl- g aq Cl- aq H3 384 kJ Mol i Give the name of 2 marks H1 .. H3 .. ii Using an energy cycle diagram, calculate the molar enthalpy of solution of sodium chloride 3 marks 4. Study the flow diagram below and use it to answer the questions that follow. A. Name substance; H , T F 3 marks b. State the conditions for 2 marks i. Step 1 ii. Step 2 c. Write an equation for the reaction in 2 marks i. Step 6 ii. Step 5 d. Draw the structural formula of substance M 1 mark e.


Describe three successive tests he would carry out to confirm the solid is zinc and give the observations expected in each test. 3marks Test Procedure Expected observation 1 2 3www.freekcsepastpapers.comPage 171 7. The diagram below shows the laboratory preparation of ammonia gas. Study it and use it to answer the questions that follow. A. Name the reactants used 1 mark b. Give the role of calcium oxide 1 mark c. State 2 physical properties of ammonia gas 1 mark d. Write an equation for the reaction 1 mark e. Ammonia reacts with oxygen in the presence of a catalyst to produce nitric V acid industrially. I Name the catalyst used 1 mark ii Describe how the product in e above is converted to nitric V acid 2 marks f. Ammonia and sulphuric VI acid are reacted to form a fertilizer. I Write an equation for the reaction. 1 mark ii Calculate the volume of ammonia required at STP to manufacture 1500kg of the fertilizer at STP N 14.0, H 1.0, S 32, O 16.0, MGV at STP 22.4L 3 marks www.freekcsepastpapers.comPage 172 MURANG A EXTRA COUNTY SCHOOLS EXAMINATION. Kenya Certificate of Secondary Education 233 3 Chemistry PAPER 3 PRACTICAL 1. You are provided with; solution P, potassium manganate VII solution Q, containing 6.3 g litre of dibasic acid H2X.nH2O Solution R, containing 4.0 g litre of Sodium hydroxide solution. You are required to determine: a The value of n in H2X.nH2O b How the rate of reaction of solution P with solution Q varies with change in temperature. Procedure 1 Fill the burette with solution Q. Pipette 25cm3 of solution R into a conical flask and titrate solution Q with solution R using phenolphthalein indicator. Record your results in table I below and repeat the titration two more times and complete the table: Table I.


Phenolphthalein indicator 2. Source of heat 3. 2M Pb NO3 2 aq 4. 2M HNO3 aq 5. 0.5M Ba NO3 2 aq 6. 2M Ammonia solution 7. 2M NaOH 8. Acidified KMnO4 solution 9. 2M HCl aq NOTES 1. Solution Q is 0.05M oxalic acid 2. Solution P is 0.01M potassium manganate vii solution. 3. Solution R is 0.1M sodium hydroxide solution. 4. A hot Water bath prepared by placing about 200 cm3of water in a 250ml beaker. 5. Solid V mixture NH4 2SO4 and Al2 SO4 3 in the ratio 1: 1 6. Solid T is maleic acid crystals. 7. Acidified KMnO4 is made by dissolving 3.169 of the solid KMnO4 in about 500 cm3of 2M H2S04 acid and diluting to one litre of solution. Www.freekcsepastpapers.comPage 187 MUMIAS WEST JOINT EVALUATION TEST, 2023 Kenya Certificate of Secondary Education 233 1 CHEMISTRY Paper 1 Theory TIME: 2 HOURS 1. A mixture of magnesium powder and copper powder was reacted with dilute hydrochloric acid. The solution was then filtered. Name: a i The residue 1mk ii The filtrate 1mk b Write an ionic equation for the reaction that takes place 1mk 2. Aluminium chloride solution changes the blue litmus paper red. Explain this observation 2mks 3. The diagram below shows the set-up that can be used to prepare and collect oxygen gas. Study it and answer the questions that follow. A Identify two mistakes from the diagram which must be corrected for one to collect dry oxygen gas 2mks b What property of oxygen gas makes it possible to be collected over water? 1mk 4. The table below gives information on four elements by letters K, L, M and N. Study it and answer the questions that follow.


1mk 4. The table below gives information on four elements by letters K, L, M and N. Study it and answer the questions that follow. The letters do not represent the actual symbol of the elements. Element Electron arrangement Atomic radius nm Ionic radius nm Q 2.8.2 0.136 0.065 R 2.8.7 0.099 0.181 S 2.8.8.1 0.203 0.133 T 2.8.8.2 0.174 0.099 a Which two elements have similar chemical properties? Explain 2mks b What is the most likely formula of the oxide of R? 1mk c Which element is a non-metal. Explain 1mk 5. A fixed mass of a gas has a volume of 250cm3 at a temperature of 270C and 750mmHg pressure. Calculate the volume the gas would occupy at 420C and 750mmHg pressure. 3mks 6. Zinc metal and Hydrochloric acid react according to the following equation Zn s 2HCl aq ZnCl2 aq H2 g 1.96g of zinc were reacted with 100cm3 of 0.2M Hydrochloric acid, a Determine the reagent that was not enough 2mks www.freekcsepastpapers.comPage 188 b Calculate the total volume of hydrogen gas that was liberated at S.T.P conditions Zn 65.4, molar gas volume 22.4 litres at S.T.P 1mks 7. A Explain how a sample of CH3CH2OH could be distinguished from a sample of CH3COOH by a chemical test 2mks b Give the name of the type of compound formed when the a above are reacted . 1mk 8. A polymer has the following structure a Draw the repeating unit of the polymer 1mk b A sample of this polymer is found to have a molecular mass of 5194.


A Explain how a sample of CH3CH2OH could be distinguished from a sample of CH3COOH by a chemical test 2mks b Give the name of the type of compound formed when the a above are reacted . 1mk 8. A polymer has the following structure a Draw the repeating unit of the polymer 1mk b A sample of this polymer is found to have a molecular mass of 5194. Determine the number of monomers on the polymer H 1.0, C 12.0, N 14.0 2mks 9. Describe how the following reagents can be used to prepare lead II sulphate: Solid potassium sulphate, solid lead II carbonate, dilute nitric acid and distilled water. 3mks 10. Explain why the enthalpy of neutralization of ethanoic acid with sodium hydroxide is different from that of Hydrochloric acid with sodium hydroxide. 3mks 11. Use the information below to answer the questions that follow: Equation: Enthalpy of formation. I H2 g O2 g H2O l H1 -286kJmol-1 ii C s O2 g CO2 g H2 -394kJmol-1 iii 2C s 3H2 g O2 g C2H5OH l H3 -277kJmol-1 Calculate the molar enthalpy of combustion of ethanol, given that: C2H5OH l 3O2 g 2CO2 g 3H2O l 3mks 12. The structure shown below represent two cleansing agents A and B. Which cleansing agent would be more suitable for washing in water containing magnesium sulphate? Explain 2mks b Identify the Soapy detergent . 1mk 13. M grammes of a radioactive isotope decayed to 5 grammes in 100 days. The half life of the isotopes is 25 days. A What is meant by half life?


M grammes of a radioactive isotope decayed to 5 grammes in 100 days. The half life of the isotopes is 25 days. A What is meant by half life? 1mks b Calculate the initial mass M of the radioactive isotope 2mks 14. Complete the diagram to show how a sample of dry ammonia gas can be prepared in the laboratory. 3mks 15. 30cm3 of hydrogen gas was exploded with 10cm3 of oxygen gas at room temperature and pressure. Calculate the total volume of the mixture at; a 1000C 2mks b 700C 1mk www.freekcsepastpapers.comPage 189 16. Study the scheme below and answer the questions that follow a Write the formula of the cation present in the yellow solution F 1mk b What property of chlorine is shown in step I 1mk c Write an equation for the reaction in step III 1mk 17. A student set up the experiment below to collect gas K. The glass wool was heated before heating the zinc powder. A Why was it necessary to heat the moist glass wool before heating the zinc powder 2mk b What observations were made in the test tube 1mk 18. Using dots and crosses to represent the outermost electrons, draw the structure to show the bonding in CO2. C 6, O 8 . 3mks 19. Calculate the mass of nitrogen IV oxide gas that would occupy the same volume as 10g of hydrogen gas at the same temperature and pressure. H 1.0, N 14.0, O 16.0 3mks 20. Below is a table of reduction potentials and voltage of some half cells.


2mks 27. In an experiment to study the properties of concentrated nitric acid, a mixture of the acid and wood charcoal was heated in a boiling tube. A What observations were made? Explain your answer 2mks b Write an equation for the reaction that took place in the boiling tube 1mk www.freekcsepastpapers.comPage 191 MUMIAS WEST JOINT EVALUATION TEST, 2023 Kenya Certificate of Secondary Education 233 2 Chemistry PAPER 2 Theory TIME: 2 HOURS 1. Study the flow chart that follows and answer the questions that follow. A Name the following 3mrks i Reagent E and Reagent S ii Compound F iii Reagent G iv Compound B v Compound C vi Compound O b Name the type of reaction in steps 2, 4. 8 and 9. 2mrks c State any one condition necessary for steps 3, 4, 8 and 10 to take place 2mrks d Draw the structure of compounds P, F and O 3mrks e Steps 5 and 9 are similar and lead to the same products. State and explain one difference in the observations made when steps 5 and 9 are separately carried out. 2mrks f Write chemical equations for the reactions that take place in steps 2 and 8. 2mrks 2. A Distinguish between an element and a molecule. 2mks b The diagram below represents part of the periodic table. Use it to answer the questions that follow. The letters do not represent the actual symbols of the elements F C G H D E J K i Which metallic element shown on the table has the highest electrical conductance? Explain 2mks www.freekcsepastpapers.comPage 192 ii Write the formula of the compound formed between E and G 1mk iii How do the first ionization energies of elements C and D compare? Explain. 2mks iv The melting point of E and K are 1120oC and -34oC respectively. In terms of structure and bonding, explain why there is a large difference in the melting point of E and K.


Explain. 2mks iv The melting point of E and K are 1120oC and -34oC respectively. In terms of structure and bonding, explain why there is a large difference in the melting point of E and K. 2mks v Indicate on the grid the position of element L which forms L3- ions with electronic configuration 2.8.8. 1mk vi Element J reacts with dilute sulphuric VI acid at room temperature to produce 0.4dm3 of gas. Determine the mass of J which was reacted with dilute sulphuric VI acid. Molar gas volume at rtp is 24dm3, relative atomic mass of J 27 3mks 3. The graph that follows shows the solubility curves for some three common salts. Study it and answer the questions that follow. A Which of the three salts has the highest solubility at 200C? 1mrk b Which of the three salts has the lowest solubility at 300C? 1mrk c State the temperature at which the solubility of sodium chloride is the same as that of potassium nitrate and state the solubility of these salts at this temperature. 2mrks d The solubility of potassium nitrate is 137g 100g of water at 700C and 110g 100g of water at 600C. The solubility of potassium chlorate is 32g 100g of water at 700C and 25g 100g of water at 600C. Predict what will happen when 100g of water containing 130g of potassium nitrate and 20g of potassium chlorate is cooled from 700C to 600C. 2mrks e 100g of water at 600C containing 100g of potassium nitrate and 22g of potassium chlorate v was cooled to 200C. All the crystals formed were filtered. I Calculate the mass of each salt filtered out. 2mrks ii Determine the composition of the solution at 200C after filtration. 2mrks iii Determine the total mass of the solution at 200C after filtration. 2mrks 4 a Define the following terms. 3mrks i. Enthalpy of formation. Ii. Enthalpy of combustion.


A Identify the following substances 2mks i Solid A ii Gas D. iii Solid Q. iv Solution M. b Write a chemical equation for the reaction in step I. 1mk c Write chemical equation for the formation of the following compounds. 3mks i Solid G. ii Gas D. iii Light blue solution C. iv State the confirmatory test for oxygen gas. 1mk v Write the ionic equation for reaction taking place in process P. 1mk vi State two uses of oxygen. 2mks 7. A State Charles law 1mk b Complete the following table by interconverting the following temperatures and filling in the missing volumes assuming that the volumes apply to the same mass of gas at constant pressure. 5mrks Temperature in 0C Temperature in K Volume in litres 195 156 8 312 -234 c A certain gas occupies 700cm3 at -700C. If pressure remains constant, at what temperature in 0C will its volume increase by a factor of 3? 4mrkswww.freekcsepastpapers.comPage 195 MUMIAS WEST JOINT EVALUATION TEST, 2023 Kenya Certificate of Secondary Education 233 3 Chemistry PRACTICAL Paper 3 TIME: 2 HOURS 1. You are provided with: Sodium hydroxide labeled solution A 0.128M hydrochloric acid labeled solution B Carboxylic acid labeled solution C Solution D prepared by diluting 25cm3 of solution A with distilled water to 150cm3 of solution You are required to: i Standardize solution D with solution B ii Determine the ratio between sodium hydroxide, solution A and the carboxylic acid, solution C iii Determine the concentration of C in moles per litre. Procedure 1 Fill the burette with solution B. Pipette 25cm3 of solution D into 250cm3 conical flask. Add 2 drops of phenolphthalein indicator and titrate with solution B. Record your results in table 1 below. Repeat the titration two more times and complete the table.


Add 2 drops of phenolphthalein indicator and titrate with solution B. Record your results in table 1 below. Repeat the titration two more times and complete the table. Table 1 4marks I II III Final burette reading cm3 Initial burette reading cm3 Volume of solution B used cm3 a Determine the average volume of solution B used. 1mark b Calculate the concentration in moles per litre of sodium hydroxide in : i Solution D 2marks ii Solution A 2marks PROCEDURE 2 Using a clean burette, place 16cm3 of solution C into a boiling tube. Take the initial temperature of the solution in the boiling tube and record it in the table 2. Using a clean measuring cylinder, measure 4cm3 of solution A into 100cm3 beaker and add it to solution C in the boiling tube. Stir the mixture immediately with the thermometer and record in Table 2 the maximum final temperature reached. Repeat the experiment with the other set volumes of solution C and A in Table 2 and complete it. Rinse the thermometer and the boiling tube with distilled water after each experiment. Table 2 6Marks Volume of solution C, cm3 16 12 8 6 4 2 Volume of solution A, cm3 4 8 12 14 16 18 Final temperature OC Initial temperature OC Change in temperature, c On the grid provided, plot a graph of change in temperature vertical axes against the volume of sodium hydroxide, solution A d From the graph, determine the volume of sodium hydroxide solution A required to neutralize the carboxylic acid 1mark www.freekcsepastpapers.comPage 196 e Calculate the volume of carboxylic acid, solution C used for neutralization 1mark f Calculate the: i Ratio between the volumes of solution A and C 2marks ii Concentration in moles per litre of carboxylic acid, solution C Assume the volume ratio is the same as the mole ratio 2marks 2. You are provided with solid E. Carry out the tests below and record your observations and inferences in the spaces provided. A Divide E into halves.


Filter funnel 3. Pipette 25cm3 4. One pipette filler 5. 0.3g of solid G 6. Two 250ml conical flasks 7. About 120ml of solution A 8. About 100ml of solution B 9. About 60ml of solution C 10. About 100ml of solution D 11. One 10ml measuring cylinder 12. Thermometer -10 110OC 13. 100ml plastic beaker 14. Two boiling tubes 15. One test tube holder 16. 2 red and 2 blue litmus papers 17. 1g of solid E 18. 0.5g of solid F 19. 6 clean dry test tubes 20. About 500ml distilled water Access to the following: 1. 2.0M sodium hydroxide supplied with a dropper 2. 0.5M Lead II nitrate supplied with a dropper 3. Bunsen burner 4. Phenolphthalein indicator supplied with a dropper 5. 2M sulphuric VI acid 6. Bromine water supplied with a dropper 7. Acidified potassium manganate VII supplied with a dropper NOTES AND PREPARATION 1. Solution A is made by dissolving 48g of sodium hydroxide in 500cm3 of distilled water and diluting to make one litre. 2. Solution B is made by dissolving 12cm3 of concentrated hydrochloric acid in about 600cm3 of distilled water and diluting it to one litre. 3. Solution C is prepared by dissolving 76g of oxalic acid in 600cm3 of distilled water and diluting to one litre 4. Solution D is prepared by dissolving 4g of sodium hydroxide in 600cm3 of distilled water and diluting to one litre. 5. Solid G is NaHCO3 6. Solid E is calcium chloride 7. Solid F is benzoic acidwww.freekcsepastpapers.comPage 213 KIRINYAGA WEST SCHOOL BASED EXAMINATION, 2023 233 1 CHEMISTRY PAPER 1 Theory TIME: 2 HOURS Instructions to candidates a. Answer ALL the questions. B. Mathematical tables and electronic calculators may be used.


100cm3 of oxygen diffuse through an opening in 10 seconds while 150cm3 of unknown gas takes 12 seconds. Calculate the molecular mass of gas x. O 16.0 3mks 6. In a titration experiment 25cm 3 of sodium hydroxide solution containing 8.0g per litre was required for complete neutralization of 0.245g of diabasic acid. Calculate the relative molecular mass of the acid. Na 23, O 16, H 1.0 3mks www.freekcsepastpapers.comPage 214 7. Use the information below and answer the questions that follow. A Identify solid x. 1mk b Name gas w. 1mk c Write an equation between yellow solid and sulphuric VI acid. 1mk 8. Oxide of M was found to react with dilute hydrochloric acid and potassium hydroxide. What type of oxide is M oxide? 1mk 9. A 100g of radioactive substance was reduced to 6.25g within 15.6 years. Calculate the half life of the substance. 2mks b Study the nuclear reaction given in the scheme below and answer the question that follow. C127 Write an equation for the nuclear reaction in step II. 1mk 10. The information below relates to elements D E F and H. The letters do not represent the actual symbols of the elements. I. E displaces H from an aqueous solution containing ions H. ii. Hydrogen gas reduces heated oxide of D but doesn t reduce heated oxide of H. iii. F liberates hydrogen gas from cold water but E doesn t. a Write an equation for the reaction between E and ions of H. Both B and D are in group II of the periodic table. 1 mk b Arrange the elements in order of their increasing reactivity. 1mk 11. The table below shows some information about elements A1, A2, A3 and A4 which are in the same group of the periodic table. Use the information to answer the questions that follow. Element 1st ionization energy kJ Mol A1 500 A2 420 A3 400 A4 520 i. What is meant by the term ionization energy?


Use the information to answer the questions that follow. Element 1st ionization energy kJ Mol A1 500 A2 420 A3 400 A4 520 i. What is meant by the term ionization energy? 1mk ii. Select the most reactive element. Give a reason for your answer. 1mk iii. Arrange the element according to increase in atomic radii. 1mk 12. A factory uses 200kg of ammonia each day to produce 120kg of nitrogen II oxide. Calculate the percentage yield of nitrogen II oxide. 3mks 13. Dry hydrogen chloride gas was passed over heated iron turnings as shown in the diagram below. A What was observed in the combustion tube during the experiment? 1mk b Write down the equation for the reaction taking place in the combustion tube. 1 mk c Identify the colour of the flame D. 1mk Step 1 Step 2 Heat Iron fillings Dry hydrogen chloride Flame Dwww.freekcsepastpapers.comPage 215 14. A gaseous hydrocarbon contains 80 carbon by mass. Given that 2dm3 of the compound at r.t.p has a mass of 2.5g. Calculate the molecular formula of the compound. C 12, H 1, Molar gas volume at r.t.p 24dm3 3mks 15. A When potassium nitrate is heated it decomposes. Write a balanced equation for the thermal decomposition of potassium nitrate. 1mk b How would you test for the gas produced in the process? 1 mk c State one use of the gas formed on decomposition. 1mk 16. Study the scheme below and answer the questions that follow. A Identify gas C. 1 mk b State one disadvantage of using platinum asbestos catalyst. 1 mk c Give the most appropriate catalyst. 1 mk 17. Study the flow chart below and answer the questions that follow. I. Give; I. The name of process that takes place in step I and II. 1 mk Step I Step II 1 mk II. The name and formula of substance N. 1 mk ii. The relative molecular mass of K is 15680. Calculate the number of monomers that make up K.


1 mk ii. The relative molecular mass of K is 15680. Calculate the number of monomers that make up K. 1mk 18. Below is a flow chart that shows the process of obtaining substance C from ammonia gas at an optimum temperature of 9000C and in presence of a catalyst. A Name raw materials used in Haber process. 1mk b Identify catalyst used to convert ammonia into substance c. 1mk c Write an equation leading to formation of substance C. 1mk 19. When hydrogen peroxide is mixed with little manganese IV oxide, a colourless gas is evolved. A Identify the gas. 1mk b What is the purpose of manganese IV oxide? 1 mk c How is the gas a above prepared in large scale? 1mk 20. Hydrogen sulphide gas was bubbled in a test tube containing a solution of Nitric V acid. A State and explain the observation that was made. 2mks b Write an equation for the reaction that took place. 1mk www.freekcsepastpapers.comPage 216 21. A Name two gaseous pollutants emitted from a car exhaust. 1mk b What is a pollutant? 1 mk 22. A In the space provided below draw a diagram to represent the apparatus that can be used to prepare hydrogen gas from a reaction of steam and metal x that is divalent. 2 mks b Write a balanced chemical equation for a above . 1 mk 23. The table below shows the relative molecular masses and the boiling points of; Explain why the boiling point of butan 1 ol is higher than that of butane. 2mks 24. Study the thermochemical equations below and answer the questions that follow.


The table below shows the relative molecular masses and the boiling points of; Explain why the boiling point of butan 1 ol is higher than that of butane. 2mks 24. Study the thermochemical equations below and answer the questions that follow. C s O 2 g ----- CO 2 g H C -39.3kJ Mol H 2 g O 2 g ------ H2O g H C - 286kJ Mol 3C s 4H 2 g ------- C3H 8 g Hf 103.6kJ Mol Calculate the heat of combustion of propane C3H8 3mks 25. Study the figure below and answer the questions that follow. I. Name process T. 1 2 mk ii. Name the substance represented by R. 1 2 mk iii. Write the formula of complex ion present in solution W. 1 mk iv. Write the equation for the reaction taking place in step P. 1 mk 26. The following equations show the dissociation of two acids. I. rH aq r- aq H aq II. PH aq P- aq H aq a Which of the two acids is a weak acid? Give a reason for your answer. 2 mks b Give a difference between a dilute acid and weak acid. 1mk 27. Element Z has three isotopes 36Z, 38Z 40Z and the abundance of the element is 0.34 , 0.06 and 99.6 respectively. Calculate the relative atomic mass of Z. 2mks 28. Describe the chemical tests that would distinguish between C3H8O and C2H4O2. 2 mks 29. Study the information given in the table below and answer the questions that follow.


Describe the chemical tests that would distinguish between C3H8O and C2H4O2. 2 mks 29. Study the information given in the table below and answer the questions that follow. Half reactions Electrode potential E V P 2 aq 2e - P s 0.34 Q aq e- Q s 0.80 R 2 aq 2e- R s -2.87 V 2 aq 2e- V s -0.13 W 2 aq 2e- W s -2.71 U3 aq e- U 2 s 0.68 Construct an electrochemical cell that will produce the largest e.m.f. 3mks www.freekcsepastpapers.comPage 217 KIRINYAGA WEST SCHOOL BASED EXAMINATION, 2023 233 2 CHEMISTRY PAPER 2 Theory TIME: 2 HOURS INSTRUCTIONS TO CANDIDATES 1. Answer all questions in the English. 2. Mathematical tables and electronic calculators may be used. 3. All working must be clearly shown where necessary. 1. A The grid below shows part of the periodic table. Study it and answer the questions that follow. The letters do not represent the actual symbols of the elements. I State an element that can form an ion with a charge of -2. 1 2mk ii What type of structure will a chloride of Q have? 1 2mk iii Explain how the reactivities of V and W compare. 2mks iv Compare the atomic radius of T and S. Explain. 2mks v 2.5g of a Q react completely with 1.2dm3 of gas R at s.t.p I. Write a balanced equation for the reaction between Q and R. 1mk II. Determine the R.A.M of Q Molar Volume of a gas at s.t.p 22.4dm3 2mks b Study the information given below and answer the questions that follow.


Write a balanced equation for the reaction between Q and R. 1mk II. Determine the R.A.M of Q Molar Volume of a gas at s.t.p 22.4dm3 2mks b Study the information given below and answer the questions that follow. Formula of compound Nacl MgCl2 Al2Cl6 SiCl4 PCl5 Boiling point 0C 1470 1420 Sublimes 60 75 Melting point 0C 800 710 800 -70 90 i Why is the fomula of aluminium chloride given as Al2Cl6 and not AlCl3. 1mk ii Give a chloride that is a liquid at room temperature. Explain 1mk iii Explain the difference in melting point of NaCl and PCl5. 2mks 2. Study the flow chart below and answer the questions that follow. Www.freekcsepastpapers.comPage 218 a Identify i Substance F 1 2mk ii Liquid D 1 2mk iii Gas Y 1 2mk iv Gas X 1 2mk b Name and draw the structure of compounds; b T 2mks c X 2mks c Identify the type of reaction and condition for changing X to CH3CH2Cl. 1mk d Name the type of reaction that i Leads to the formation of CH3CH2COOH. 1mk ii Leads to the formation of substance W. 1mk d Write an equation that results in formation of product Z. 1mk e What is the effect on the continued use of substance T to the environment? Explain. 2mks 3. A The diagram below is part of a set up used to prepare and collect dry chlorine gas. I Complete the diagram to show how dry chlorine gas can be collected. 2mks ii Name another substance that can be used instead of Manganese IV oxide. 1mk ii Write an equation for the following I. Chlorine reacting with Iron. 1mk II. Chlorine reacting with hot concentrated sodium hydroxide solution.


Chlorine reacting with Iron. 1mk II. Chlorine reacting with hot concentrated sodium hydroxide solution. 1mk iv An oxide of chlorine of mass 1.83g was found to contain 1.12g of oxygen. Determine the empirical formula of the oxide. O 16, Cl 35.5 3mks v Other than manufacture of hydrochloric acid name two other uses of chlorine. 1mk b Two solutions containing cations P and Q were separately added to solutions containing chloride ions. In both cases a white precipitate was formed. To each a few drops of nitric V acid were added. The chloride compound of P and Q warmed. The chloride compound of Q dissolved while that of P did not. I Identify the metal ions of P and Q. 1mk ii Write ionic equations for the reaction that occurred when cations of P and Q reacted with chloride ions. 2mks 4. A The set up below was used during electrolysis of aqueous iron II sulphate using inert electrodes. Study it and answer the questions that follow. Concentrated HCl Manganese IV oxide Aqueous Iron II Sulphatewww.freekcsepastpapers.comPage 219 i Name a suitable material for the electrodes. 1mk ii Identify the cations present in the solution. 1mk iii On the diagram label the cathode. 1mk iv Write an ionic equation for the reaction that took place at the anode. 1mks v Explain the changes that occurred in the concentration of iron II sulphate solution during the experiment. 2mks b The information below is about the standard reduction potentials of four half cells. Study it and answer the questions that follow. Letters do not represent the actual symbols of the elements. Half cell E value V F2 aq 2e- 2F- aq 0.54 G2 aq 2e- G s -0.44 H2 aq 2e- H s 0.34 2J aq 2e- J2 g 0.00 i Identify the strongest reducing agent. Explain.


Letters do not represent the actual symbols of the elements. Half cell E value V F2 aq 2e- 2F- aq 0.54 G2 aq 2e- G s -0.44 H2 aq 2e- H s 0.34 2J aq 2e- J2 g 0.00 i Identify the strongest reducing agent. Explain. 1mk ii Write the equation for reaction which takes place when solid G is added to a solution containing H2 aq ions 1mk iii Calculate the E value of the reaction in ii above. 1mk iv If element G becomes the reference electrode calculate the new standard electrode potential for element H. 1mk c Calculate the mass of chlorine liberated during the electrolysis of molten sodium chloride when a current of 2A is passed for 4 minutes. Cl 35.5 2mks 5. A Define the following terms. I Half-life 1mk ii Nuclear fission 1mk b The table below gives percentage of a radioactive isotope of Bismuth that remains after decaying at different times. Time in min 0 6 12 22 38 62 100 Percentage of Bismuth 100 81 65 46 29 12 3 i On a graph paper plot the percentage of Bismuth remaining against time. 3mks ii Using the graph determine the original mass of the Bismuth Isotope given that the mass that remained after 70 minutes was 0.16g. 2mks c Radioactive Carbon 14 decays by emitting beta particle to form N-14, write a nuclear equation for the reaction. 1mk d State one use of radioactive Isotope in: i Medicine 1mk ii Industry 1mk 6. An excess Zinc powder was added to 200cm3 of Copper II sulphate solution. The mixture was stirred with a thermometer and the temperature noted. The temperature rose from 220C to 28.20C and 1.58g of Copper was deposited. A Write ionic equation for the reaction that took place.


The mixture was stirred with a thermometer and the temperature noted. The temperature rose from 220C to 28.20C and 1.58g of Copper was deposited. A Write ionic equation for the reaction that took place. 1mk b Why was excess Zinc powder used? 1mk c Besides the temperature rise state two other observations made as the mixture was stirred. 2mks d Using the information above calculate the molar enthalpy of deposition of copper by zinc. R.A.M of copper 63.5, Specific heat capacity 4.18KjKg-1 k-1 4mks e Using the result of d above draw an energy level diagram of deposition of copper by zinc. 2mks f If this experiment was repeated using Iron fillings instead of zinc powder how would you expect the molar enthalpy of displacement to compare with one obtained in d above. Explain. 2mks www.freekcsepastpapers.comPage 220 4. Iron is obtained from haematite using a blast furnace shown in the figure below. A State two raw materials required for the production of iron other than iron oxide. 1mk b Write an equation for the reaction in which carbon IV oxide is converted to carbon II oxide. 1mk c Explain why the temperature in the region marked Y is higher than that of the incoming hot air. 2mks d State one physical property of molten slag other than density that allows it to be separated from molten iron as shown. 1mk e One of the components of the waste gases is nitrogen IV oxide. Describe the adverse effects it has on the environment. 2mks f Iron from the blast furnace contains 5 carbon. I Describe how the car bon content is reduced. 2mks ii Why is it necessary to reduce the carbon content? 1mk www.freekcsepastpapers.comPage 221 KIRINYAGA WEST SCHOOL BASED EXAMINATION, 2023 233 3 CHEMISTRY PAPER 3 CONFIDENTIAL In addition to the sittings and apparatus found in a chemistry laboratory, each candidate will require the following; - 120 cm3 of solution T.


I Describe how the car bon content is reduced. 2mks ii Why is it necessary to reduce the carbon content? 1mk www.freekcsepastpapers.comPage 221 KIRINYAGA WEST SCHOOL BASED EXAMINATION, 2023 233 3 CHEMISTRY PAPER 3 CONFIDENTIAL In addition to the sittings and apparatus found in a chemistry laboratory, each candidate will require the following; - 120 cm3 of solution T. - 100 cm3 of solution E - 100cm3 of solution F - 3 cm of polished magnesium ribbon labelled solid M - 1 label - 50 ml burette - 25 ml pipette - 2 conical flasks - Thermometer - White file - Complete stand - 250ml volumetric flask - White plain piece of paper. -. Distilled water. -. 50ml measuring cylinder. -. 10ml measuring cylinder. -. 100ml plastic beaker - Stop watch - Filter funnel. -. 1 boiling tube. -. 5 test tubes in a rack. -. 0.2g of solid sodium hydrogen carbonate approximate . -. Solid K - Solid Q - Filter funnel - Test tube holder - 1 filter paper. -. Metallic spatula. -. Source of heat Access to: - Bunsen burner. -. 2M sodium hydroxide solution with a dropper. -. 0.5 M sodium sulphate solution with a dropper. -. 0.5M barium nitrate solution with a dropper. -. 0.5M lead ii nitrate solution with a dropper. -. Acidified potassium manganate VII solution with a dropper. -. Acidified potassium dichromate VI solution with a dropper. -. Phenolphthalein indicator with a dropper. NOTES 1. Solid Q , 1 g zinc chloride 2. Solid K, crushed paracetamol panadol 0.5g 3. Solution E is 2M hydrochloric acid. 4. Solution F is 0.2M sodium hydroxide solution. 5. Solution T is 0.15M sodium thiosulphate. 6. Solid M is 3 cm polished magnesium ribbon.


Solution T is 0.15M sodium thiosulphate. 6. Solid M is 3 cm polished magnesium ribbon. Www.freekcsepastpapers.comPage 222 KIRINYAGA WEST SCHOOL BASED EXAMINATION, 2023 233 3 CHEMISTRY PAPER 3 Practical TIME: 2 HOURS 15 MINUTES Instructions to candidates a. Answer ALL the questions. B. Mathematical tables and electronic calculators may be used. C. All working MUST be clearly shown where necessary. 1. You are provided with; - Solution E, containing 2M hydrochloric acid. -. Solution F, containing 0.2M sodium hydroxide. -. Solid M, Magnesium ribbon. -. Solution T, containing 0.15M sodium thiosulphate. You are required to; i. Determine molar heat of reaction between magnesium and hydrochloric acid. Ii. Determine rate of reaction between hydrochloric and sodium thiosulphate. Procedure 1 i Place 20cm3 of solution E into 100ml plastic beaker and measure the intial temperature of solution E. Initial temperature of solution E 0C 1 2 mk ii Add all the solid M provided to solution E and stir the mixture with a thermometer. Measure the maximum temperature of the solution. Maximum temperature of the solution 0C. 1 2 mk iii Transfer the resulting solution formed into a 250ml volumetric flask, add distilled water upto the mark. Shake the mixture well and label it as solution G. iv Fill the burette with solution G upto 0.0cm3 mark. Pipette 25cm3 of solution F into a clean conical flask and add 2-3 drops of phenolphthalein indicator. V Titrate solution G against solution F until the pink colour turns colourless. Repeat the titration two more times and record the values in table 1 below. A Table 1 4 mks Experiment i ii iii Final burette reading Initial burette reading Volume of solution G used cm3 b Calculate the average volume of solution G used. 1 mk c Calculate the number of moles of sodium hydroxide solution F used. 1 mk d Calculate the number of moles of hydrochloric acid; i. In the average volume of solution G used.