nakuru district secondary schools trial examination - KCSE Online

Name……………………………………………School…………………………………233/1CHEMISTRYTHEORYPaper 1July/August 20122 HoursIndex No…………………Candidates Signature……………Date……………………NAKURU DISTRICT SECONDARY SCHOOLS TRIALEXAMINATION -2012Kenya Certificate of Secondary Education (K.C.S.E)233/1CHEMISTRY PAPER 1THEORYPaper 1July/August 2012HoursINSTRUCTIONS TO CANDIDATES• Write your name and Index Number in the spaces provided above.• Sign and write date of examination in the spaces provided above.• Answer ALL questions in the spaces provided.• Mathematical tables and silent electronic calculators may be used.• All workings MUST be clearly shown where necessary.For Examiners use only.Question Maximum Score Candidates Score1-25This paper consists of 14 printed pagesVisit:1www.kcse-online.info for thousands of free Past papers

1 The diagram, below shows a students set-up for the preparation and collection of hydrogen Gas100cm 3 of 0.6mHclwater3.25 zincpowder(a) How would the final volume of hydrogen gas produced be affected if 80cm 3 of 0.85mhydrochloric acid was used. Show your working(3marks)……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..2 Name the process that takes place when(i) Ethanol reacts with concentrated sulphuric acid at 180 o C to form ethane(1mark)…………………………………………………………………………………………………..(ii) Ammonium chloride is heated and forms white powder on the cooler parts of the boiling tube(1mark)…………………………………………………………………………………………………(iii) Propanol reacts with propanbic acid in the presence of a catalysis to form propyl propanoate(1mark)…………………………………………………………………………………………………3ExcessIdentifyPbOSolution KVisit:1. Warm2. filterWhitesolidHeatstrongly3. cool2www.kcse-online.info for thousands of free Past papersSolid LBrown gas +Gas M

3. Identify (3marks)a) solution K…………………………………………………………………………………………b) Solid L……………………………………………………………………………………………c) Gas M……………………………………………………………………………………………4. An element in period 4 forms the oxide P 2 Oa) What is the valency of P (1mark)…………………………………...…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….......(b) What name is given to the group to which element P belongs(1mark)..................................................................................................................................................(c) Write down the electronic arrangement of P in the oxide P 2 O (1mark)…………………………………...…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….......5 Distinguish between nuclear fission and nuclear fusion (2marks)…………………………………...…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….......6 K grammes of a radio active isotope decayed to 6.5g in 100 days. The half-life of the isotopeis 25 days.(a) What is meant by half-life(1mark)......................................................................................................................................................(b) Calculate the initial mass of isotope K(2marks)…………………………………...……………………………………………………………Visit:3www.kcse-online.info for thousands of free Past papers

……………………………………………………………………………………………………………………………………………………………………………………………….......7 When 6 litres of chlorine gas were completely reacted with element D which is an alkalineearth metal,23.75g of the product were formed. Determine the relative atomic mass of theelement D. (atomic mass of chlorine =35.5 molar gas volume =24 litres) 3marks…………………………………...…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….......…………………………………...……………………………………………………………8 The diagram below shows spots of pure substance A B and C on a chromatography paper.Spot D is that of a mixtureA BC DAfter development A,B,C were found to have moved 4cm, 15cm, 3cm respectively. D. hadseparated into two spots which had moved 3cm and 4cm. On the diagram,(a)(i) show how t he position of all the spots after development.(2marks)(ii) Identify the substances in mixture D. (1mark)..............................................................................................................................................9. The sketch below shows the rate at which substance P is converted to R.. Study it andanswer the questions that followConcentrationRpVisit:4www.kcse-online.info for thousands of free Past papers

Timea) Which of the two R and P is the product? Explain (2marks..................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) Why do the two curves become horizontal after some time(1mark)................................................................................................................................................................................................................................................................................................................................................................................................................................................................10. The set up below was used to obtain a sample of iron(a) Write two equations for the reactions t hat occur in the combustion tube(2mark)...............................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) Describe a test for the gas collected in the gas jar5Visit: www.kcse-online.info for thousands of free Past papers(1mark)

.................................................................................................................................................................................................................................................................................................................................................................................................................................................................11glass wool soaked in watertest tubeexcess zinc powdergas K(a)Why was it necessary to heat the moist glass wool before heating zinc powder (1mark).................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b)Identify gas K ................................................................................................(1mark)(c) Describe a test for gas K (1mark)...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................12(a)Give the names of the following compoundsi) CH 3 CH=CH CH 2 CH 3 (1Mark)Visit:6www.kcse-online.info for thousands of free Past papers

.......................................................................................................................Oii) CH 3 CH 2 CH 2 C – OH(1mark)..................................................................................................................................(b)Ethane and ethene react with bromine according to the equation below.(i) C 2 H 6(g) + Br 2(g) C 2 H S Br (5) + HBr(ii) C 2 H 4(g) + Br 2(g) C 2 H 4 Br 2Name the type of bromination reaction that take place in (i) and (ii)(1mark)(i)...................................................................................................................................................(ii)……………………………………………………………………………………………….13 Study the scheme below and answer the questions that followSolid E + Ca(OH) 2 pasteStep IwarmAmmonia GasStep IIBubble over aluminum sulphate solution and filterSolid F(a) Identify solid E................................................................................................................( 1mark)(b) Write an ionic equation for the reaction in step II that produces solid F(1mark)Visit:7www.kcse-online.info for thousands of free Past papers

..................................................................................................................................................................................................................................................................................................................................................................................................................................................................(c) Name the nitrogenous compound formed when ammonia burns in oxygen in presence of aplatinum catalyst(1mark....................................................................................................................................................14 (a) State the type of bond in each of the following compounds (2marks)(i)(ii)(iii)Calcium fluoride (CaF 2 )..................................................................................( 1 / 2 mark)Methane (CH 4 )................................................................................................. 1 / 2 mark)Ammonium ion (NH + 4).....................................................................................(1mark)(b) Explain why the melting point of sodium is higher than that of potassium (1mark)..............................................................................................................................................................................................................................................................................................................................................................................................................................................................15 A polymeter has the following structure ;CH 2 – CH 2 – CH 2 –CH – CH- 2 CH– CH 2 – CH – CH 21 1 1 1Cl Cl Cl Cl nA sample of this polymer is found to have a molecular mass of 875.(a) Draw the structure of the monomer(1mark)..............................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) Determine the number of monomers in the polymer (C=12, Cl=35.5)(2marks)...............................................................................................................................................................................................................................................................................................................................................................................................................................................................Visit:8www.kcse-online.info for thousands of free Past papers

16 Four metals F,G,H, and J were each separately added to cold water, hot water and steam.The table below is a summary of the observation made and the formulae of the hydroxideformed.Metals Cold water Hot water steam Formula ofhydroxideF Reacts slowly Reacts fast Reacts very fast Fe(OH) 2G No reaction No reaction No reaction -H Fast Reacts veryfastReacts explosivelyHOHJ No reaction Reacts slowly Reacts fast J(OH) 2(a)Which two elements are likely to be in the same group of the periodic table (1mark).......................................................................................................................................-.....................................................................................................................................(b) Arrange the metals in the order of their reactivity (2marks)............................................................................................................................................17 Study the standard electrode potentials for the half-cells given below and answer thequestions that follow. The letters do not represent the actual symbols of the elementE VoltsN + (aq) + e N (s) -2.92J + (aq) + e J (s) +0.52K + (aq) + e ½ K 2(g) 0.00½ G 2(g) + e G - (aq) 1.36M 2+ (aq) +2 e M(s) 0.44(a) Which is the strongest reducing agent? Give a reason for your answer(1mark)..............................................................................................................................................................................................................................................................................................................(b) Which two half cells would produce the highest potential difference when combined?(1mark)Visit:9www.kcse-online.info for thousands of free Past papers

...........................................................................................................................................................................................................................................................................................................(c)Will the reaction below take place?(1mark)M (s) + 2N + (aq) M 2+ (aq) + 2N (s)--------------------------------------------------------------------------------------------------------------18 (a) Name one reagent that reacts with concentrated hydrochloric acid to produce chlorineGas( 1 mark).....................................................................................................................................................................................................................b) A student set out to prepare Iron(III) chloride using the apparatus shown in the diagrambelow.guard rubeExplain why(i) It is necessary to pass chlorine gas through the apparatus before heating begins (1 mark)..........................................................................................................................................................................................................................................................................................................(ii) Calcium oxide would be preferred to calcium chloride in the guard tube (1mark)Visit:10www.kcse-online.info for thousands of free Past papers

.....................................................................................................................................................................................................................................................................................................(c) What property of ion(III) chloride makes it possible to be collected as shown in the diagram(1mark)........................................................................................................................................................................................................................................................................................................19 The scheme below was used to prepare a cleansing agent. Study it and answer the questionsthat follow.NaOH(aq)FatBoilStep ISolution of cleansing agent and an alcoholStep IISolid cleansing agent(a) What name is given to the type of cleansing agent prepared by the method shown in the scheme(1mark).....................................................................................................................................(b)(i) Name one chemical substances added in step II(1mark)...................................................................................................................................(ii) What is the purpose of adding the chemical substance named in b(i) above(1mark)...........................................................................................................................20 (a) State Graham’s law of diffusion (1mark)............................................................................................................................................................................................................................................................................................................(b) Nitrogen diffuses through a porous plug at a rate of 10cm -3 min -1 and a gas A diffuses at therate of 5.9cm -3 min -1 . Calculate the molar mass of A. (N=14) (2marks)………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………Visit:11www.kcse-online.info for thousands of free Past papers

……………………………………………………………………………………………………………………………………………………………………………………………………………21 A hydrated salt has the following composition by mass iron 20.2%, oxygen 23.0%,sulphur 11.5% and water 45.3%. If its relative formula mass is 278(i) Determine the formula of the hydrated slat(3marks)……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..22 Study the flow chart below and then answer the questions that follow.Sugar solutionCompound ESubstance APolymerizationCrude ethanolProcess XHydrogen gasSubstance B con. H 2 SO 4Pure ethanol 90%Substance D(a)(i) Name(2marks)Visit:12www.kcse-online.info for thousands of free Past papers

Substance A.......................................................................................................Process X.............................................................................................................Substance B...............................................................................................................Substance D ...........................................................................................................(b)(i) Identify the type of polymerization that results to the formation of compound E ((½ mark)....................................................................................................................................................(ii) What is the effect of continuous use of the polymer E on the environment(½ mark)............................................................................................................................................................................................................................................................................................................23(a) Name two crystalline allotropes of sulphur(1mark).................................................................................................................................................................................................................................................................................................(b) Name two other elements that exhibit allotropy(1mark)...................................................................................................................................................................................................................................................................................................(c ) Why is surphur (vi) oxide not absorbed directly into water in the contact process (1mark)……………………………………………………………………………………………………………………………………………………………………………………………………24 State the uses of the following apparatus in chemistry (3marks)(a)A Separating funnel……………………………………………………………………………(b) A Pipette .....................................................................................................................................(c ) A Spatula ..................................................................................................................................25 A student tested the pH of five solutions using universal indicator and obtained thefollowing resultsSolution Colour pHVisit:13www.kcse-online.info for thousands of free Past papers

A Blue 10B Violet 14C Red 1D Green 7E Yellow 5(a) Which of the solution is likely to be(i) Lactic acid ........................................................................................................ (½ mark)(ii) Sodium chloride ...................................................................................................(½ mark)(b) Magnesium hydroxide is used as medication to relieve stomach acidity.(i) Write down the word equation for the reaction that occurs in the stomach when one takes inthe medicine(1mark)............................................................................................................................................................................................................................................................................................................b (ii)Explain why sodium hydroxide cannot be used for the same purpose in (b i) above (1mark)..................................................................................................................................................................................................................................................................................................................................................................................................................................................................26 what mass of copper would be deposited on the cathode when a steady current of one ampereflows for 30 minutes through copper(ii) sulphate solution.(3marks)Cu =64 IF =965000C……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..Visit:14www.kcse-online.info for thousands of free Past papers