chemistry perfect score 2011 module answer

of 43/43
1 BAHAGIAN PENGURUSAN SEKOLAH BERASRAMA PENUH DAN SEKOLAH KLUSTER JAWAPAN MODUL PERFECT SCORE 2011 CHEMISTRY [KIMIA] Set 1 Set 2 Set 3 Set 4 Set 5

Post on 06-May-2015

3.824 views

Category:

Technology

17 download

Embed Size (px)

DESCRIPTION

Chemistry Perfect Score 2011 module answer

TRANSCRIPT

  • 1.BAHAGIAN PENGURUSANSEKOLAH BERASRAMA PENUH DAN SEKOLAH KLUSTER JAWAPANMODUL PERFECT SCORE2011 CHEMISTRY [KIMIA] Set 1 Set 2 Set 3 Set 4 Set 51

2. JAWAPAN SET 1PAPER 2 : STRUCTURED QUESTIONSection ANo.AnswerMark1 (a)The formula that shows the simplest whole number ratio of atoms1 of each element in a compound.(b)H2SO4 + Zn ZnSO4 + H22(c)Heating, cooling and weighing are repeated until a constant mass is1 obtained.(d)Element CopperOxygenMass, g47.70 25.30 53.30 47.70=22.40 =5.60Mole atom22.405.60 6416= 0.35= 0.35Simplest ratio 11 Empirical formula = CuO4(e)H2 + CuO Cu + H2O2(f)To prevent the hot copper from being oxidized again. 1(g) Magnesium ribbon Heat2 TOTAL 13No. AnswerMark2 (a) (i) Al2CO3 1(ii) Al2(CO3)3Al2O3 + 3CO2 2(iii) The number of mole of Al2 (CO3) 3 = 70.2/ 234= 0.3 mol 1 Based on the balanced equation; Al2 (CO3)3 : Al2O3 1: 10.3 : 0.3 1Mass of Ag = 0.4 x 102 = 30.6 g 1(iv)Based on the balanced equationAl2 (CO3)3 : CO21 : 3 0.3 : 0.61Volume of CO2 = 0.9 x 24= 21.6 dm31 = 21600 cm31(b) (i) Zinc carbonate1(ii)Zinc oxide and carbon dioxide 12 3. (iii) ZnCO3 ZnO + CO2 1TOTAL 12No. AnswerMark3 (a) (i)The number of protons found in the nucleus of an atom 1(ii) 7 1(b)133 Q 16(c)P and S // Q and R1(d) (i)Q and R 1(ii) Have same proton number but different nucleon number // 1 Have same number of protons but different number of neutrons(e) (i)Melting point : 63 OC [values & unit must be correct] 1(ii) Section Physical state ABSolid DELiquid and gas 1(iii) the heat energy absorbed by the particles is used1to overcome the forces of attraction between particles 1TOTAL 10No. AnswerMark4 (a)Sodium and magnesium // sodium and aluminium // magnesium and 1 aluminium(b)Halogen 1(c)2.8.3 1(d) (i)Sodium, magnesium, aluminium, chlorine, argon 1 Atomic size decreases(ii) From left to right : The proton number // the positive charge increases from sodium to argon 1 The forces of attraction by the nucleus on the electrons (nuclei attraction)1 in the first three occupied shells become stronger(e) (i)Sodium burnt rapidly and brightly with a yellow flame //1 White fumes liberated // white solid formed(ii)2Na + Cl2 2NaCl[Formula of reactants and product are correct] 1[Balanced equation]1has high melting / boiling point // conduct electricity1(iii) in molten state or aqueous solution // soluble in waterTOTAL103 4. No.AnswerMark5 (a) (i)X1 (ii)8 valence electron // electron arrangement 2.8 // achieve octet electron 1 arrangement(b)Covalent 1(c) (i) VW4 ( (b)1 (a) i i(ii) ) ( 1+1 WWV W W(iii)has low melting / boiling point // cannot conduct electricity1 in molten and solid state . // insoluble in water// soluble in organic solvent.(d) (i)Ionic compound 1 (ii)Atom U donate one electron to form U+ ion1 Atom W accept one electron to form W- ion1 U+ ion and W- ion attracted to each other by strong electrostatic force /1 ionic bond. (iii)11U W [Number of electron each shells are correct] [Number of charge symbol are correct] TOTAL13 4 5. PAPER 2: ESSAY QUESTIONSection BNo. Answer Mark6 (a) Group 171Period 31Has seven valence electrons.1Has three shells occupied with electron 1 (b) (i) Between Y and X 1.Atom Y has 1 valence electron and atom X has 7 valence electron1 2. to achieve octet electron arrangement 1 3. Atom Y loses/donates/transfers 1 electron to form ion Y+1 4. Atom X gains/receives 1 electrons from atom Y to form ion X-1 5 Y+ ion and X- ion are attracted by a strong electrostatic force / ionic bond 1 6. Diagram+Y X1 (ii) Between W and X 1. Atom W has 4 valence electrons and atom X has 7 valence electrons.1 2. Each atom W contributes 4 electrons whereas each atom X contributesone electron for sharing. 3. to achieve octet electron arrangement1 4. Four atoms of X share a pair of electrons with one atom W to form a1WX4 molecule / Diagram1XW X X W W W X WMolecules WX4 5 6. (c) Compound P : ionic bond1Compound Q : Covalent bond 1Melting PointCompound PIons are held by strong electrostatic forces.More energy is needed to overcome these forces.1Compound Q 1Molecules are held by weak intermolecular forces.Only a little energy is required to overcome the forces.Or 1Electrical conductivity 1Compound PIn molten state or aqueous solution , there are free moving ions 1Ions carry charge 1Compound Q 1In molten and solid states , no free moving ions 1exist as moleculeTOTAL20No.Answer Mark7 (a) (i)2.8.7, Chlorine1+1(ii) 2Fe + 3Cl2 2FeCl3 Correct formulae of reactants and product 1 Balanced1(b) (i)Z,Y,X 1 Z more reactive than X1 Atomic size of Z bigger than atomic size X1 Valence electron become further away from nucleus 1 Valence electron to be more weakly pulled by the nucleus1 Valence electron can be released more easily in atom Z1(ii) same/similar1 Same valence electron 1(c)X : 2.4 1 Y : 2.6 1 to achieve octet electron arrangement one X atom contributes four electron and each two Y atoms 1 contributes two electrons for sharing 1 Group 161 Period 21 6 valence electron1 2 shells occupied with electrons1 TOTAL206 7. PAPER 2: ESSAY QUESTIONSection CNo. AnswerMark8 (a) (i)Dilute acid: Hydrochloric acid / Sulphuric acid/ Nitric acid1 Metal N: Magnesium / zinc 1(ii) Anhydrous calcium chloride1 To dry the hydrogen gas 1(iii) Example: Copper(II) oxide1Copper ion is reduced// reduction process1Because oxidation number of copper decrease from +2 to 0Hydrogen is oxidised// oxidation process 1Because oxidation number of hydrogen increase from 0 to +1 1Hydrogen is reducing agent 1Copper(II) ion// Copper(II) oxide is oxidising agent 1(b) (i)Relative Molecular mass of (CH2)n = 561 (12 + 2) n = 56n=4Molecular formula = C4H8 1(ii)Unglasedporcelain chips Glass wool soaked in butanol Heat Water 2 Procedure: 1.A small amount of glass wool soaked in butanol is placed in a boiling tube.1 2.The boiling tube is clamped horizontally1 3.The unglazed porcelain chips are placed in the middle section of the boiling tube.1 4.The boiling tube is closed with a stopper fitted with a delivery tube 1 5.The unglazed porcelain chips are heated strongly. Then, the glass wool is warmed gently to vaporize the propanol. 1 6.The gas released is collected in a test tube. 1TOTAL 20 7 8. No.Answer Mark9 (a) (i)Formula that shows the simplest ratio of the number of atoms for each 1 element in the compound.(ii) Copper(II)oxide // lead(II)oxide 1 CuO + H2 Cu + H2O // PbO + H2 Pb + H2O1+1(b) (i)Magnesium oxide / zinc oxide 1(ii)Procedure: 1. Clean magnesium / zinc ribbon with sand paper 1 2. Weigh crucible and its lid1 3. Put magnesium ribbon into the crucible and weigh the crucible withits lid 1 4. Heat strongly the crucible without its lid1 5. Cover the crucible when the magnesium starts to burn and lift/raise 1 the lid a little at intervals 6.Remove the lid when the magnesium burnt completely 1 7.Heat strongly the crucible for a few minutes 1 8.Cool and weigh the crucible with its lid and the content 1 9.Repeat the processes of heating, cooling and weighing until a constant 1 mass is obtained 10. Record all the mass1 Result: DescriptionMass/g1Crucible + lidxCrucible + lid + magnesiumyCrucible + lid + magnesium oxidez Calculation: Element Mg O Mass, g y-x z-y Moley-x z-y24161 =0.1=0.1 Simplest ratio1 11 Empirical formula: MgO Max 10(c)Element CHMass (%) 84.6 15.4Number of moles84.6/12 15.4/11=7.05=15.41Mole ratio12 Empirical formula : CH2 1 RMM of (CH2)n = 70 1 [ 12 + 2]n = 7014 n = 70n = 5 1 Molecular formula : C5H10120 8 9. JAWAPAN SET 2PAPER 2 : STRUCTURED QUESTIONSection ANo.AnswerMark1 (a)Cell II1(b) (i)Magnesium electrode1(ii) eV 1 MagnesiumCopper electrode electrode (iii) Copper electrode thicker // Brown solid deposited1 (c) 1. Correct formulae of reactant and product1 2. Balanced equation 1Cu2+ + 2e Cu (d) (i) Electrical energy to chemical energy 1 (ii)Blue colour remain unchange1 (iii) 1. Concentration / Number of mole of Cu2+ ion remain unchanged 1 2. Rate of Cu2+ ion discharge at cathode is the same as rate of Cu atom ionize at anode 1 TOTAL10No. Answer Mark2 (a) (i)Iodine 1 r: formula/iodide/iodine gas (ii)MnO4 - + 8 H+ + 5 e Mn2+ + 4 H2O 1 (iii) +7 +21 reduction1 (iv)Potassium chloride // iron(II) sulphate // [any reducing agent]1(b)(i) Zinc 1 (ii)1. Correct formulae of reactant and product1 2. Balanced equation 12 Zn + O2 2 ZnOa: 2 J + O2 2 JO (iii) K,J, L 1 (iv)Predict : no changes 1 r: no reaction Reason : L is more reactive than J/zinc1 r: more electropositive TOTAL11 9 10. PAPER 2 : ESSAY QUESTIONSection BNo. AnswerMark3 (a)1.Propanone is a covalent compound1 2.Propanone exist as molecule // No freely moving ion in propanone1 3.Sodium chloride is an ionic compound 4.Sodium chloride solution has freely moving ion1 1(b) (i)Properties Cell XCell Y1. Type of cellVoltaic cellElectrolytic cell2. EnergyChemical electrical Electrical chemical change 13. ElectrodesAnode: APositive terminal: C // Copper 1 Cathode: BNegative terminal: D // Zinc4. Ions in Cu2+, SO42-, H+ and OH- Cu2+, SO42-, H+ and OH- ions 1 electrolyte ions5. HalfAnode:Positive terminal: 1 equationCu Cu2+ + 2eCu2+ + 2e Cu Cathode:Negative terminal1 Cu2+ + 2e CuZn Zn2+ + 2e6. Observation Anode:Positive terminal: 1 Copper ecomes thinner Copper plate becomes thicker1 Cathode:Negative terminal: 1.6 Copper becomesZinc becomes thinner thicker(c)1. Ag, M, L1 2. L is more electropositive than silver 1 3. L displace silver from silver nitrate solution1 4. M is more electropositive than silver 1 5. M displace silver from silver nitrate solution1 6. M is less electropositive than L1 7. M cannot displace L from L nitrate solution 1(i Copper // Cu 1i)TOTAL20No. AnswerMark4 (a) (i) 1.Correct formulae of reactant and product 12.Balanced equation1Zn+ 2e Zn2+3.Correct formulae of reactant and product 14.Balanced equation1Pb2+ + 2e Pb(ii)1.Zinc is oxidized 12.Zinc atom donates / losses electrons 13.Lead(II) nitrate / Pb2+ is reduced 14.Lead(II) nitrate / Pb2+ receives electrons 1(b) (i) 1. Green colour of iron(II) sulphate change to brown 12. Correct formulae of reactant and product13.Balanced equation1Cl2 + 2Fe2+ 2Cl- +2Fe3+4.Colourless solution of potassium iodide change to brown15.Correct formulae of reactant and product 16.Balanced equation1Cl2 + 2I- 2Cl- +I210 11. (ii)Test tube P : Cl- ion and Fe3+ ion 1+1Test tube Q : Cl- ion and I2 1+1(iii) 1. Add starch solution12. Dark blue precipitate formed 1 TOTAL20PAPER 2 : ESSAY QUESTIONSection CNo. Answer Mark 2+5 (a) (i) 1. Cu // copper(II) ion 1Equation2. Correct formula of reactant and product 13. Balance 1 Cu2+ + 2e Cu4. Copper1(ii)1. Oxygen12. Insert glowing splinter into the test tube13. Glowing splinter relights 1(iii) 1. NO3- // nitrate ion 12. Oxygen13. OH- ion is discharge14. OH- ion is place lower than NO3- ion in the electrochemical series1Equation5. Correct formula of reactant and product 16. Balance 1 4 OH- 2 H2O + O2 + 4 e(b) Diagram1. Functional apparatus12. Label 1 ImpurePure copper copperCopper(II)sulphate solution3. Pour [50 200 cm3] copper(II) sulphate solution into a beaker14. Connect pure copper as cathode and impure copper as anode 15. Dip both pure and impure copper into copper(II) sulphate solution 16. Anode : Cu Cu2+ + 2e17. Cathode : Cu2+ + 2e Cu1TOTAL 20 11 12. No.Answer Mark6 (a) (i)Metal P : Tin // Lead // Copper 1 Metal Q : Magnesium // Aluminium // Zinc1(ii) Exp I 1. Metal P is less electropositive than iron1 2. Iron is oxidized 1 3. Iron losses electron // Fe Fe2+ + 2e 1 4. Dark blue precipitate indicates the presence of Fe2+ ion 1 Exp II 5. Metal Q is more electropositive than iron1 6. Metal Q is oxidized // Metal Q losses electron 1 7. Water and oxygen receive electron // 2H2O+O2 + 4 e 4OH-1 8. Pink colouration indicates the presence of OH- ion 1(b) (i)1. Bromine is reduced 1 2. Bromine molecule receives electron // Oxidation number of bromine1decrease / 0 -1 3. Iron(II) sulphate / Fe2+ is oxidized 1 4. Fe2+ losses electron // Oxidation number of iron increases / +2 +31 5. Correct formula of reactant and product 6. Balanced equation1Br2 + 2Fe2+ 2Br-+ 2Fe3+1 7. Brown colour of bromine decolourise 8. Green colour of iron(II) sulphate change to brown 11(ii) 1. Add sodium hydroxide solution 1 2. Brown precipitate formed1TOTAL20 12 13. JAWAPAN SET 3PAPER 2 : STRUCTURED QUESTIONSection ANo. AnswerMark1 (a)(i) Solution in test tube C1 (ii)Solution in test tube A1(b)1. Higher than pH value of 0.1 moldm-3 HCl // The pH is 3/4/5/61 2. Ethanoic acis is a weak acid// Etanoic acid ionizes partially in water to produce 1 low concentration oh hydrogen ion 3. The lower the concentration, the lower the pH value 1(c ) (i)Magnesium chloride1 (ii)Mg + 2 H+ Mg2+ + H2 1. Correct formula of reactant and product 1 2. Balanced equation 1 (iii) No of mole, HCl = 0.1 x 5 / 1000 = 0.0005 mol 1 Based on balanced equation, 2 mol of HCl : 1 mol of H20.0005 mol of HCl : 0.00025 mol of H2 // mol of H2 = 0.005/2 = 0.0025Volume of hydrogen gas = 0.00025 x 24 dm3 1= 0.006 dm3 // 6 cm31(d)White precipitate1 TOTAL12No.Answer Mark2 (a)(i)Solvent P: Water 1Solvent Q: methyl benzene / propanone / suitable organic solvent 1 (ii) Effervescence / gas released // magnesium ribbon dissolved 1 (iii)1. In the presence of solvent P/water , ethanoic acid ionize to form H+ ion. 12. H+ ion causes the ethanoic acid to show its acidic properties 13. In solvent Q, ethanoic acid exist as molecule// hydrogen ion does not present 1(b)(i)1. pH value increase / bigger12. The lower the concentration of acid the higher the pH value 1 (ii)(0.5)(V) = (0.04)(250) //1V = 20 cm3 1 3Alkali that ionize/dissociate completely in water to produce high concentration of hydroxide11(a) ions.(b) Alkaline / alkaline solution11(c) P: ion1Q: molecule 12(d) No1Because there are no hydroxide ions in the solution// ammonia exist in the form of molecule.12 13 14. (e) (i) 1 1. Colourless gas bubbles are released.// efeervesence 1(ii) Mg + 2HCl MgCl2 + H21. Correct formula12. Balanced equation12. Mol of Mg = 2.4/24 // 0.1 mol1 43. Volume of H2 = 0.1 24 dm3 = 2.4 dm31 Total11NOANSWERMARK 4(a) (i) Green1(ii) Double decomposition reaction 1(b) (i) carbon dioxide 1(ii) CuCO3 CuO + CO2 1. Reactants and products are correct 1+ 1 2. Equation is balanced(iii)Copper(II)carbonate Heat Lime water - Labelled diagram2 - Functional(c) 1 mol CuCO3 = 12.4/124 = 0.1 molMol of CuCl2 = 0.1 x 135gMass = 13.5g 3 10No.AnswerMark5 (a)Mg + 2HClMgCl2+ H2 1+1(b)(i) 0.4/24 = 0.0167 mol 1 (ii The number of mole of HCl = MV/1000 = 1x 50/1000 = 0.05 mol 1 )(c)From the chemical equation 1 mol of magnesium produce 1 mol hydrogen If 0.0167 mol produce 0.0167 mol hydrogen 1 Volume of hydrogen = 0.0167 x 24 dm3= 0.4 dm3/ 400 cm31(d)I400 /100 =4 cm3s-1 1 II 400 /60 = 6.67 cm3s-11(e)As catalyst 1(f)The temperature of hydrochloric acid1 The concentration of hydrochloric acid1 TOTAL11 14 15. No.Answer Mark6 (a) The heat released when 1 one mole of copper is displaced from copper (II) sulphate 1solution by zinc.(b) Cu2+ + Zn Cu + Zn2+1(c) The blue colour of the solution become colourless//Brown deposit is formed// 1The polystyrene cup become hot//The reading of the thermometer increase1(d) (i) Heat release = 50 x 4.2 x 10 1= 2100 J(ii) The number of moles = 50 x 0.5= 0.025 mol 10001(iii) Heat of displacement = 2100= -84000 J0.025 H = 84.0 kJ/mol 1(e) To ensure all the copper(II) sulphate solution reacted completely1(f)Energy Zn + Cu2+ H= - 84.0 kJ/mol Zn2+ + Cu1+1 TOTAL 10 No. Answer Mark7 (a) Graph : Axes labeled with units1All points plotted correctly 1& Shape of graph correct 1 (i)50 cm3 ( marked on the graph)1 (ii) NaOH+HClNaCl + H2OMol of NaOH = 50 x 1 = 0.0511000From the equation : 1 mol NaOH : 1 mol HCl0.05 mol NaOH : 0.05 mol HCl1+1Concentration HCl = 0.05 x 1000 = 1 moldm-350 (c)To ensure uniform temperature of mixture in the polystyrene cup1(d) All the sodium hydroxide has reacted completely1(e)(i)0.1 mole of NaOH when reacted releases 5.6 kJ1Therefore for 1 mole of NaOH reacted, 5.6/0.1 = 56 kJ heat energy released 15 16. (ii) Energy NaOH + HCl H= - 56.0 kJ/mol 1+1 H2O + NaCl(i)Less than 5.6 kJ 1(ii) - Hydrochlolric acid is strong acid dissociates completely in water ; ethanoic 1 acid is a weak acid dissociates in partially water -Part of the heat released during neutralisation is absorbed to ionise further 1 ethanoic acid molecules, therefore heat released will be less than 5.6 kJTOTAL14PAPER 2 : ESSAY QUESTIONSection BNo. AnswerMark8 (a)(i) Label axes with units1 All points are transferred correctly 1 Shape of the graph is smooth and correct 1 (ii) 2.5 cm3 1 (iii) moles of Pb2+ ions = 2.5 x 1.0 / / 0.00251 1000 moles of I- ions = 5 x 1.0 // 0.00510001Pb2+ : I-0.0025 : 0.0005 11 :21(b) Test tube 1:1. Ion exist : K+, I- and NO3-2. All lead(II) nitrate reacts completely 13. Excess of potassium iodide 14. Solution contains soluble salt of potassium iodide and potassium nitrate 11Test tube 5:5. Ion exist : K+ and NO3-6. All lead(II) nitrate reacts completely and all potassium iodide reacts 1 completely 17. Solution contains soluble salt of potassium nitrate1Test tube 7:8.Ion exist : K+, Pb2+ and NO3- 19.All potassium iodide reacts completely110. Excess of lead(II) nitrate111. Solution contains soluble salt of lead(II) nitrate and potassium nitrate1Max 10 16 17. No. AnswerMark9(a)(i) Size of the reactant/the total surface area of the reactant 1Concentration of the reactant 1Temperature of the reactant 1Catalyst1(ii)Temperature : 450-550oC 1Catalyst : iron 1Pressure : 200 atm1 (b)(i) The axes are labeled together with its unit 1 The scale is correct1 The points are transferred correctly11 The curve is smooth(ii)Average rate of reaction for experiment I = 26.01 210 = 0.12 cm3 s-1 1Average rate of reaction for experiment II = 26.0 1501 = 0.17 cm3 s-1[correct unit]1(iii) 1. The rate of reaction for Experiment II is higher than in Experiment I12. The concentration of HCl in Experiment II is more/higher than in 1 Experiment I3. The number of hydrogen ion/ H+ per unit volume of the solution in11 Experiment II is more than in Experiment I4. The frequency of collisions between hydrogen ion and calcium carbonate 1 in Experiment II is more than in Experiment I5. The frequency of effective collisions hydrogen ion and calcium carbonate in Experiment II is more than in Experiment I TOTAL20PAPER 2 : ESSAY QUESTION Section C No.Answer Mark10 (a) (i)Experiment I hydrochloric acid or1Experiment II sulphuric acidMg + 2HCl MgCl2 + H21+1(ii)The number of mole of HCl = MV/1000= 1.0 x 50 = 0.05 mol 1000 or 1The number of mole of H2SO4 = MV/1000= 1.0 x 50 = 0.05 mol1000(iii) The rate of reaction is the change of volume of hydrogen gas per unit time 1 17 18. (b) (i)Volume of hydrogen/ cm3Experiment II Experiment I11 Time/s 1. Curve with label 2. Axis with title and correct unit (ii)1. Sulphuric acid in experiment II is diprotic acid, hydrochloric acid inexperiment I is monoprotic acid//Concentration of hydrogen ion, H+in experiment II is higher than experiment I 2. The number of hydrogen ion per unit volume in experiment II ishigher than experiment I 3. Frequency of collisions between hydrogen ions and magnesium atomsin experiment II is higher than experiment I 4. Frequency of effective collisions between hydrogen ions andmagnesium atoms in experiment II is higher than experiment I 5. Rate of reaction in experiment II is higher than experiment I5 (c)Diagram : Functional apparatus set-up 1 Label correctly1..2Procedure :1. A burette is filled with water and inverted over a basin containing water. The burette is clamped vertically to the retort stand.12. The water level in the burette is adjusted and the initial burette reading is recorded.13. 50 cm3 of 0.2 moldm-3 hydrocloric acid / sulphuric acid is measured and poured into a conical flask 4. 4. 5 cm of magnesium ribbon are added into the conical flask1 5. 5. close conical flask immediately with the stopper fitted with 1 delivery tube. 16. At the same time the stopwatch is started shake the conical flask. 17. The burette readings are recorded at 30 second intervals for 5 1 minutes7 max 5 Time/s0 30 60 90 120 150 1801 Volume of gas / cm3 TOTAL 20 No. AnswerMark11 (a) Water on the wet shirt evaporated1 Evaporation absorbs heat energy from body1 (b) (i) C2H5OH + 3 O2 2 CO2 + 3 H2OH = - 1,376 kJ / mol 1+ 1 1. Heat of combustion for propanol is higher than ethanol1 2. No. of carbon and hydrogen atoms per molecule propanol is higher118 19. than ethanol3. No. of mole of CO2 and H2O produced during combustion of1 propanol is more than ethanol 1..44. Formation of CO2 and H2O releases heat energy(ii) Diagram labelled and functional 1 1.2 Material : Water , ethanol Apparatus : spirit lamp. weighing balance, copper can, clay-pipe1 triangle, thermometer, wind shield1..2Procedure :1. Measure (100 250) cm3 of water and pour into the copper canand initial temperature is recorded after 5 minutes12. Weigh the spirit lamp filled with ethanol3. Light the spirit lamp to heat the water in the can and stir 14. Extinguish the spirit lamp when the temperature increase reaches130C, record the maximum temperature of water reached5. Weigh the spirit lamp with its remain.1Result :7. The initial mass of the spirit lamp + ethanol = a gThe final mass of the spirit lamp + ethanol = b g8. The mass of ethanol burnt = (a-b) g 19. The initial temperature of water = t1CThe maximum temperature of water = t2C110. Increase in temperature of the water = (t2 t1) tC Calculation : 1 RMM of ethanol C2H5OH = 4611.The no. of mol of ethanol burnt = ab = y mol6012.The released heat = mc = 100 x 4.2 x t1= xJ x 1 13.The heat of combustion of propanol = - J mol-1 or -Z y 1kJ mol-1 13 max 8 TOTAL 20 No. Answer Mark12 (a) Exothermic reaction is a reaction that releases heat to the surrounding1 The total energy content of the products is lower than the total energy content of the 1 reactants Endothermic reaction is a reaction that absorbs heat from the surrounding1 The total energy content of the products is higher than the total energy content of the1 reactants (b) A reacts with B to form C and D1 A and B are the reactants while C and D are the products 1 Heat energy is absorbed from surrounding //It is an endothermic reaction 1 Total energy content of C and D/ product is higher than total energy content of A and B/ 1 reactants When reaction occurs, the temperature of mixture of solutions increases / becomes hot1 (any 4 of the above) (c) 1. 1 mole of silver nitrate solution produces 1 mole of Ag+ ion1 2. 1 mole of sodium chloride solution produces 1 mole of Cl- ion 1 19 20. 3. One e mole of potassium chloride produces 1 mole of Cl- ion 14. The heat of precipitation of silver chloride is heat that released when 1 mole of AgCl1 is formed from Ag+ ion and Cl- ion // Ag+ + Cl- AgCl5. Number of mole of AgCl produced in bothe reactions are the same, heat released are 1 the same. Max 4 (d)Materials : calcium nitrate solution, sodium carbonate solution1Procedures :- measure 50 cm3 of 1.0 mol/ dm3 Ca(NO3)2 solution and 50 cm3 of 1.0 mol / dm3 1Na2CO3 solution separately and poured into a plastic cup- measure and record the initial temperature of both solutions after 5 minutes 1- pour quickly and carefully Ca(NO3)2 solution into the plastic cup that contains1Na2CO3 solution and stir continuously- measure and record the lowest temperature reached1Tabulation of data : Initial temperature of Ca(NO3)2 / oC 1 Initial temperature of Na2CO3 / oC 2 Average initial temperature / oC(1 + 2)/2 3 Lowest temperature of the mixture / oC 4 1 Change in temperature / oC 3- 4Calculation :No. of moles of CaCO3 = No. of moles of Ca(NO3)2 1 = mv/1000 = 1.0(50)/1000 = 0.05heat change mc(4 3)1= x kJheat of reaction = + x kJmol-10.05 = + y kJmol-1 TOTAL 20 No. AnswerMark13 a (i)1. Zinc nitrate, zinc sulphate 12. Zinc carbonate1 (ii)I :Sodium carbonate solution/ potassium carbonate solution / ammonium 1 carbonate solution1 II : Sulphuric acid (iii) 1. 50 cm3 of 1 mol dm-3 magnesium nitrate solution is measured and1poured into a beaker 2.50 cm3 of 1 mol dm-3 Sodium carbonate solution/ potassium carbonatesolution / ammonium carbonate solution solution is measured and1poured into the beaker.1 3. The mixture is stirred with a glass rod and a white solid, magnesium 1carbonate is formed. 1 4. The mixture is filtered 5. and the residue is rinsed with distilled water 1 6. The white precipitate is dried by pressing it between filter papers. 1620 21. c (i)1. nitrate ion / NO3- ion 1 2. Add dilute sulphuric acid followed by iron(II) sulphate solution into test tube 1 containing salt X solution 3. Add a few drops of concentrated sulphuric acid through the wall of test tube 1 4. A brown ring is formed. 1(ii) 1. Zn2+ , Pb2+ , Al3+ 1 2. Add ammonia solution into test tube containing salt X solution until excess1 3. White precipitate dissolves in excess ammonia solution showing the 1presence of Zn2+ ions 4. White precipitate insoluble in excess ammonia solution showing the 1presence of Pb2+ and Al3+ ions.1 5. Add potassium iodide solution into test tube containing salt X solution 1Yellow precipitate formed showing the presence of Pb2+ ions // 6. No change showing the presence of Al3+ ions. 2021 22. JAWAPAN SET 4PAPER 2 : STRUCTURED QUESTIONSection ANoAnswerMark1 (a)Compound that contains only carbon and hydrogen 1 Has double bonds between carbon carbon atoms1 (b) Alkene1 (c) Propene 1 (d) (i) Hydrogenation / Addition reaction 1 (ii) 1 (e)(i)C3H6 + 9/2 O2 3CO2 + 3H2O or2 2C3H6 + 9O2 6CO2 + 6H2O (ii) 2 .1 1 No. of mole of C3H6=42= 0.05 Volume of gas CO2= 0.05 x 3 x 24= 3.6 dm31TOTAL10 NoAnswer Mark2 (a)Ethanol 1(b)Hydroxyl group1(c)(i) Oxidation 1(ii) Orange colour of potassium dichromate (VI) solution turns to green1 (iii) 1H O H CC O HH(d) (i)Esterification1 (ii)Ethyl ethanoate 1 (iii) Pleasant smell1 (iv)CH3COOH + C2H5OH CH3COOC2H5 + H2O 2TOTAL10 22 23. No. ExplanationMark3 (a)(i) Haber process 1 (ii)N2 + 3H22NH3 Correct formula1 Balanced 1 (iii) 450 oC --- 550oC 1 Vanadium(V) oxide1 (iv)As a fertiliser1(b) (i) Polyvinyl chloride // polychloroethene 1 (ii) 1(c)Correct arrangement1Tin atom Correct label1 Copper atom TOTAL 10No.ExplanationMark4 (a) (i) glycerol 1(ii) saponification / alkaline hydrolysis1(iii)to cause precipitation of soap1(b) (i)1 X: detergent 1 Y :soap(ii) magnesium stearate or calcium stearate1(iii)Mg2+ and Ca2+ 1+1(iv) causes water pollution / non-biodegradable1 TOTAL 923 24. PAPER 2 : ESSAY QUESTIONSection BNo Answer Mark5 (a)(i)14.3 % 1(ii) Element C H Mass/ % 85.714.3 1 No. of moles85.7 14.3 = 7.14= 14.312 1 2 Ratio of moles/ 7.1414.3 Simplest ratio =1=2 7.147.14 3 Empirical formula = CH2RMM of (CH2)n= 56 .............1 [(12 + 1(2)]n = 56 14n = 56 566 max 5 n = 14 = 4 ..1Molecular formula : C4H8 ..1(iii)1+1 1+1But-1-ene But-2-ene Max 42-methylpropene(iv)Compound M (Butene, C4H8) has a higher percentage of carbon atom intheir molecule than butane, C4H10 .1 4(12)% of C in C4H8=x 100% 4(12) 8 48=x 100% 56= 85.7%14(12)% of C in C4H10 = x 100% 4(12) 10 48=x 100% 58= 82.7%..1.....3(b) (i) Starch 1Protein1(ii)H H CH3 HI IIIC = C C = CII1HH1..22-methylbut-1,3-diene or isoprene(c) (i) Rubber that has been treated with sulphur1 24 25. In vulcanised rubber sulphur atoms form cross-links between the rubber1(ii) molecules These prevent rubber molecules from sliding too much when stretched 1TOTAL 20No. ExplanationMark6(a) Examples of food preservatives and their functions: Sodium nitrite slow down the growth of microorganisms in meat 1+1 Vinegar provide an acidic condition that inhibits the growth ofmicroorganisms in pickled foods1+1 (b) (i) Paracetamol1 Codeine1 (ii)To follow the instructions given by the doctor concerning the dosage and 1 method of taking the medicine To visit the doctor immediately if there are symtoms of allergy or other side1 effects of thye medicine (iii) If the correct dosage is not given by the doctor, it will cause abuse of the 1 medicine. For instance, if the child is given a overdose of codeine, it may lead to addition. If the child is given paracetamol on a regular basis for a long time, it may cause skin rashes, blood disorders and acute inflammation of the pancreas. 1 (c)Type of foodExamples FunctionadditivesPreservatives Sugar, saltTo slow down the growth2 of microorganismsFlavourings Monosodium To improve and enhanceglutamate, spice,the taste of food2garlicAntioxidantsAscorbic acidTo prevent oxidation of2 foodDyes/ ColouringsTartrazine To add or restore theTurmeric colour in food 2 Disadvantages of any two food additives: Sugar eating too much can cause obesity, tooth decay and diabetes1 Salt may cause high blood pressure, heart attack and stroke.1 Tartrazine can worsen the condition of asthma patients - May cause children to be hyperactive MSG can cause difficult in breathing, headaches and vomiting. TOTAL20PAPER 2 : ESSAY QUESTIONSection CMarQuestions Marking criteriaks7(a) (i) 1. Sulphur is burnt in air to produce sulphur dioxide // 1 2. Burning of metal sulphides/zinc sulphide / lead sulphide produce sulphur1dioxide 11 3. Sulphur dioxide is oxidised to sulphur trioxide in excess oxygen1 4. Sulphur trioxide is dissolved in concentrated sulphuric acidto form oleum. 5. The oleum is diluted with water to produce concentrated sulphuric acid25 26. (ii)H2SO4 + 2NH3 (NH4)2SO4Formula for reactants and product correct 1Balanced1(b) 1. Bronze is harder than copper 12. Atoms of pure copper are same size and arrange in layers 13.when force applied the layers will slide. 114. In bronze tin atom has different size compare to pure copper15. and interrupt the orderly arrangement of pure copper.max4(c) Procedure:1. Iron nail and steel nail are cleaned using sandpaper.12. Iron nail is placed into test tube A and steel nail is placed into test tube B.13. Pour the agar-agar solution mixed with potassium hexacyanoferrate(III) 1+ 1 solution into test tubes A and B until it covers the nails.4. Leave for 1 day. 15. Both test tubes are observed to determine whether there is any blue spots formed or if there are any changes on the nails. 16. The observations are recorded1Results: Test tube The intensity of blue spots1AHigh 1B Low1Conclusion:Iron rust faster than steel. TOTAL 20NoAnswerMark8 (a) (i) X - any acid methanoic acid1Y - any alkali ammonia aqueous solution1(ii)1. Methanoic acid contains hydrogen ions12. Hydrogen ions neutralise the negative charges of protein membrane13. Rubber particles collide,14. Protein membrane breaks15. Rubber polymers combine together 1 5 max 4(iii) Ammonia aqueous solution contains hydroxide ions1Hydroxide ions neutralise hydrogen ions (acid) produced by activities of1bacteria(b) (i) Alcohol 1(ii)Burns in oxygen to form carbon dioxide and water1Oxidised by oxidising agent (acidified potassium dichromate (VI) solution) to 1form carboxylic acid(iii) Procedure:1. Place glass wool in a boiling tube32. Pour 2 cm of ethanol into the boiling tube3. Place pieces of porous pot chips in the boiling tube4. Heat the porous pot chips strongly5. Heat ethanol gently 6 max 56. Using test tube collect the gas given offDiagram: 26 27. Porous pot chips Glass wool soaked with ethanol Heat HeatWater[Functional diagram] .1 ...2[Labeled porous pot, water, named alcohol, heat] .1Test:Put a few drops of bromine water .....1Brown colour of bromine water decolourised.....1 ...2Total2027 28. JAWAPAN SET 5PAPER 3 SET 1EXPLANATIONSCORE1. (a)[Able to record all reading accurately with unit](i) Sample answerExperimentMetal X Metal Y3I 1.70 cm 1.40 cmII1.75 cm 1.45 cmIII 1.75 cm 1.45 cm[Able to record all reading correctly without unit]2[able to record three to five reading correctly1No response or wrong response0 EXPLANATION SCORE1(a) [Able to construct a table to record the diameter of the dents and average(ii) diameters for material X and Y that contain: 1. correct title 2. Reading and unit Sample answer:MaterialDiameter of the dents(cm)Average 12 3diameter,(cm)X1.70 1.751.75 1.73 3Y1.40 1.451.45 1.43 [Able to construct a table to record the diameter of the dents and average2 diameters for material X and Y that contain 1. title 2. Reading [Able to construct a table with at least one title / reading1 No response or wrong response 0 EXPLANATION SCORE1.(b)[Able to state correct observation] 3 Sample answer: The diameter of dents made on material Y is smaller than material X// The diameter of dents made on material X is bigger than material Y [Able to state correct observation, incompletely] 2 Sample answer: The diameter of dents made on material Y is smaller// The diameter of dents made on material X is bigger [Able to state an idea of the observation]1 Sample answer: The diameter of dents for Y is small// The diameter of dents for X is big No response or wrong response 0 28 29. EXPLANATIONSCORE1.(c)[Able to state the inference correctly]3 Sample answer: Material Y is harder than material X// Material X softer than material Y [Able to state the inference correctly/2 Sample answer: Material Y is harder // Material X softer [Able to state an idea of inference. 1 Sample answer: Material Y is hard// Material X is soft No response or wrong response0 EXPLANATIONSCORE1.(d)[Able to state the correct operational definition for alloy] 3 1. what should be done and 2. what should be observe correctly Sample answer: When the weight of 1 kilogram is dropped at height of 50 cm to hit the ball bearing which is taped onto the alloy block using cellophane tape a smaller dent is formed. [Able to state the meaning of alloy, incompletely] 2 Sample answer: Material that form small dent is hard [Able to state an idea of alloy] 1 Sample answer: Alloy form dent//alloy is hard No response or wrong response0KK0508 EXPLANATIONSCORE1.(e)[able to give all three explanations correctly]3 Sample answer: 1. atoms in material X are in orderly arrangement 2. atoms in material Y are not in orderly arrangement 3. layer of atoms in material Y difficult to slide on each other [able to give any two explanations ] 2 [able to give any one explanations ] 1 No response given / wrong response 029 30. EXPLANATIONSCORE 1.(f) [Able to state any alloy for material Y and its major pure metal for materials X correctly]3 Sample answer: Material X: copper // iron// any suitable metal Material Y: bronze/ brass//stainless steel// any suitable alloy for pure metal given. [Able to state any alloy for material Y and its major pure metal for materials X correctly]2 Sample answer: Material X: tin/ zinc// chromium / nickel // any suitable metal Material Y: bronze// brass//stainless steel// any suitable alloy for pure metal given. [Able to state any alloy for material Y and its major pure metal for materials X correctly]1 Sample answer: Material X: magnesium // aluminium//zinc // any metal Material Y: pewter // bronze // stainless steel //any alloy No response given / wrong response 0 EXPLANATIONSCORE1.(g)[Able to state the relationship correctly between the manipulated variable and responding3 variable with direction] Sample answer: The harder/ softer the material, the smaller / bigger the diameter of the dent. [Able to state the relationship correctly between the manipulated variable and responding2 variable with direction] Sample answer: Alloy/ pure metal will form smaller/ bigger dent than pure / alloy // The smaller / bigger the diameter of the dent, the harder/softer the material [able to state the idea of hypothesis] 1 Sample answer: Y is harder // X is softer // alloy is harder No response given / wrong response 01.(h)EXPLANATION SCORE[Able to state all the three variables and all the three actions correctly] 3Sample answer: Names of variablesAction to be taken (i) manipulated : (i) the way to manipulate variable: Type of materials / material X and YChange pure metal/ alloy with alloy /pure metal (ii) responding:(ii) what to observe in the responding variable: Diameter of dentThe diameter of the dent formed on material X and Y. (iii) controlled: (iii) the way to maintain the controlled Mass of the weight // height of the weightvariable: // size of steel ball bearing.Uses same mass of weight // same height of weight // same size of steel ball bearing[able to state any two variables and any two actions correctly] 2[able to state any one variablesand any two action correctly] 1No response given / wrong response0 30 31. 2. (a)EXPLANATIONSCORE[Able to state 4 inferences correctly] 3Test tube Inference AIron (II) /Fe2+ ions formed / produced // iron / Fe rusted / oxidized BIron (II) /Fe2+ ions are not formed / produced // iron / Fe does not rusted /oxidizedC Iron (II) /Fe2+ ions are not formed / produced // iron / Fe does not rusted /oxidizedD Iron (II) /Fe2+ ions formed / produced // iron / Fe rusted / oxidized[Able to state 3 inferences correctly]2[Able to state 1 inferences correctly]1No response given / wrong response02.(b)EXPLANATION SCORE[able to explain a difference in observation correctly between test tube 1 and 2] 3Sample answer:Iron / Fe in test tube A rust / oxidized because iron is in contact with less electropositive metal, butiron in test tube B does not rust / oxidized because iron is in contact with less electropositive metal.[able to explain a difference in observation correctly between test tube A and B incompletely]2Sample answer:Iron / Fe in test tube A rust / oxidized but iron in test tube B does not rust / oxidized[able to explain a difference in observation correctly between test tubeA1 and B] 1Sample answer:Iron / Fe / nail / metal rust / oxidized // iron/ Fe/ nail/ metal does not rust / oxidizedNo response given / wrong response02.(c)EXPLANATION SCORE[Able to state the hypothesis correctly]3Sample answer:When a more/ less electropositive metal is in contact with iron / Fe, the metal inhibits/ speed uprusting of iron.//When a more / less electropositive metal is in contact with iron/ Fe, rusting of iron is faster / slower//The higher /lower the metal in contact with iron/ Fe in electrochemical series than iron /Fe ,therusting of iron/ Fe is slower / faster[Able to state the hypothesis less correctly] 2When a more/ less electropositive metal, the metal inhibits/ speed up rusting of iron.//The rusting of iron/ Fe is slower / faster if a more / less electropositive metal in contact with iron/Fe .[Able to give an idea of hypothesis ] 1Sample answer:Different metal in contact with iron, will cause iron to rust// metal can cause iron rust.No response given / wrong response0 31 32. 2.(d)EXPLANATIONSCORE[able to state all the variable in this experiment correctly]3Sample answer:(i) manipulated variable:Type/different metal(ii) responding variable:Rusting // presence of blue colour(iii) constant variable:Size/mass of iron nail // type of nail // medium in which iron nail are kept// temperature[able to state any two the variable in this experiment correctly]2[able to state any one the variable in this experiment correctly]1No response given / wrong response 02.(e)EXPLANATIONSCORE[able to state the operational definition for the rusting of iron nail correctly ] 31. What should be done and2. what should be observe correctlySample answer:When iron nail is in contact with copper/tin/less electropositive metal and immersed in potassiumhexacyanoferrate (III) solution, blue colouration is formed[able to state the operational definition for the rusting of iron nail less correctly ]2Sample answer:Rusting of iron is the formation of blue colouration when iron nail is in contact with different metal.[able to state the operational definition for the rusting of iron nail correctly ] 1Sample answer:Rusting of iron is the formation of blue colouration.No response given / wrong response 02.(f)EXPLANATIONSCORE[able to classify all the three metals correctly]Metal that can provide sacrificialMetal that cannot provide sacrificial3protection to ironprotection to iron Y X Z[able to classify any two metals correctly]2[able to classify any one metal correctly] 1No response given / wrong response 032 33. 2.(g) EXPLANATIONSCORE [Able to compare the intensity of blue colour and relate the intensity of blue colour with the3 concentration of Fe2+ accurately ] Sample answer: The intensity of blue colouration after two days is higher. The concentration of iron (II) ion is higher.[Able to compare the intensity of blue colour and relate the intensity of blue colour with the 2 concentration of Fe2+ correctly] Sample answer: The intensity of blue colouration after two days is higher. The number of iron (II) ion is higher. [able to state an idea of the intensity of blue colour and relate the intensity of blue colour with the 1 concentration of Fe2+ correctly] Sample answer: The intensity of blue colouration after two days is higher // The number of iron (II) ion is higher. No response given / wrong response0 3 (a) KK051021 Statement of problem EXPLANATION SCORE[Able to make a statement of the problem accurately and must be in question form]Suggested answer:3Does a different type of alcohols have different heat of combustions? //How does the number of carbon atom per molecule of alcohol affect the heat of combustion ?[Able to make a statement of the problem but less accurate//Accurate statement of the problem butnot in question form. ]Suggested answer: 2How does the number of carbon per molecule of alcohol affect the heat of combustion?//Does theincrease in the number of carbon per molecule of alcohol increases the heat of combustion?[Able to state an idea of statement of the problem]Suggested answer: 1Alcohols have different heat of combustion.No response given / wrong response0 3(b) KK051202 Stating variablesEXPLANATION SCORE[Able to state all the three variables correctly]3Suggested answer:Manipulated variable: Different types of alcohols//Different alcohols such as ethanol, propanol and butanol.Responding variable: Heat of combustion//Increase in temperatureFixed variable: Volume of water // type of container/ size of container[Able to state any two of the variables correctly] 2[Able to state any one of the variables correctly] 1No response given / wrong response 0 3 (c) KK051202 Stating hypothesisEXPLANATION SCORE[Able to state the relationship between manipulated variable and responding variable correctly]3Suggested answer:When the number of carbon per molecule of alcohol increases, the heat of combustion increases.[Able to state the relationship between manipulated variable and responding variable but in reverse2direction]Suggested answer:The heat of combustion increases when the number of carbon per molecule of alcohol increases.//Different types of alcohols has different heat of combustion.[Able to state an idea of the hypothesis] 1Suggested answer:Alcohols have different heat of combustion.No response given / wrong response033 34. 3(d) KK051205 List of substances and apparatus EXPLANATIONSCORE[Able to state the list of substances and apparatus correctly and completely] 3Suggested answer:Ethonol, propanol, butanol, water, [metal] beaker, spirit lamp, thermometer, weighing balance,wooden block, tripod stand, wind shield, measuring cylinder.[Able to state the list of substances and apparatus correctly but not complete] 2Suggested answer:Ethanol, propanol, butanol, water, [metal] beaker, spirit lamp, thermometer, weighing balance.[Able to state an idea about the list of substances and apparatus]1Suggested answer:Ethanol/propanol/butanol/water, beaker, thermometer.No response given / wrong response03(e) KK051204 Procedures EXPLANATIONSCORE[Able to state a complete experimental procedure] 3Suggested answer: 1. [200 cm3] of water is poured into a [copper] beaker. 2. Initial temperature of the water is recorded. 3. A spirit lamp is half filled with ethanol. 4. Weight the spirit lamp with ethanol and record the mass 5. The spirit lamp is put under the copper can and ignites the wick immediately. 6. The water is stirred and the flame is put off after the temperature has increased by 30oC. 7. The highest temperature of the water is recorded 8. Immediately weight the spirit lamp and record the mass. 9. The experiment is repeated t by replacing ethanol with propanol and butanol.[Able to state the following procedures]21, 2, 4, 5,7,8[Able to state the following procedures]12, 4, 5, 7No response given / wrong response03(f) Tabulation of dataEXPLANATION SCORE[Able to exhibit the tabulation of data correctly with suitable headings and units ] Types of InitialHighestInitial mass of Final mass of oo alcohols temperature/ C temperature/ C spirit lamp/g spirit lamp/g Ethanol Propanol Butanol3[Able to exhibit the tabulation of data less accurately with suitable headings without units ]2 Types of Initial Highest Initial massFinal mass of alcohols temperature temperaturer of spirit lamp spirit lamp[Able state an idea about the tabulation of data] 1 Alcohol Temperature MassNo response given / wrong response0 34 35. PAPER 3 SET 2QuestionRubric ScoreAble to record the burette readings accurately with 2 decimal places. ExperimentI II III1(a) Initial burette 1.00 cm313.50 cm326.00 cm33 reading Final burette 13.50 cm3 26.00 cm338.50 cm3 readingAble to record the burette reading correctly with 1 decimal place//any 5 2readings correctlyAble to record any 4 burette readings correctly1Wrong response or no response0QuestionRubric ScoreAble to construct a table with the following information:31. Accurate titles and units:2. Burette readings and volume of acid used/cm3Sample answer: Experiment I II III Initial burette1.0013.5026.00 reading/cm31(b) Final burette13.50 26.0038.50 3 reading/cm Volume of acid 12.50 12.5012.50 used/cm3Able to construct a with correct titles and burette readings and volume of 2acid used (without units)Able to construct a table with a least a title and a burette reading.1Wrong response or no response0QuestionRubric ScoreAble to calculate correctly the molarity of acid with the following steps: 3Step 1: MaVa = 1M bV b 1Step 2: Ma = 1.0 x 251(c)12.5Step 3: 2.0 mol dm-3Able to show any 2 steps correctly.2Able to show any 1 step correctly. 1Wrong response or no response0Question RubricScore Able to state the operational definition for neutralization accurately. 3 Sample answer: When 12.5 cm3 of hydrochloric acid 1.0 mol dm-3 is added to 25 cm3 sodium hydroxide 1.0 mol dm-3 with a few drops of phenolphthalein, colourless solution turns pink. Able to state the operational definition less accurately.2 Sample answer:1(d)) When hydrochloric acid is added to sodium hydroxide solution, the solution turns pink Able to state the idea for neutralisation. 1 Sample answer Acid react with alkali Wrong or no response0QuestionRubric Score 35 36. 1(e)Able to give the volume and explaination correctly with following aspects:3 1. 6.25 cm3 2. Sulphuric acid is a diprotic acid 3. Concentration of H+ ions is doubleAble to give any two of the above aspects 2Able to give aby one of the above aspects 1Wrong response or no response 0QuestionRubric Score1(f)Able to state the three variables correctly. 3Sample answerManipulated variable: Type of acids//Hydrochloric acid, ethanoic acidResponding variable: pH valuesFixed variable: Concentration of acidsAble to give any two variable correctly 2Able to give one variable correctly 1Wrong response or no response 0QuestionRubric ScoreAble to state the hypothesis accurately. 3Sample answerWhen the concentration of hydrogen ion in acid is higher, , the pH valueis lower// The higher the concentration of hydrogen ion, the lower the pHvalue1(g)Able to state the hypothesis less accurately.2Sample answer;The strong acid has lower pH value // The pH value of weak acid is higher.Able to give an idea of hypothesis 1Sample answerDifferent acid has different pH valueNo response or wrong response0 Question Rubric Score1(h) Able to classify all the substances correctly.3 Sample answer:Substances with pH less than 7 Substances with pH more than 7Ethanoic acidAmmonia solutionNitric acidBarium hydroxide Able to classify any 3 substances correctly 2 Able to classify any two substances correctly 1 Wrong response or no response 0 36 37. Question RubricScore2(a)Able to state the inference accurately 3Sample answerWhen alcohol react with ethanoic acid, ester is formed//Esters have sweet pleasantsmell propertyAble to state the inference less accurately 2Sample answerReaction between alcohol and ethanoic acid produced sweet pleasant smellproductAble to give an idea of making an inference 1Sample answerEster formedWrong response or no response 0 QuestionRubricScore2(b)Able to construct a table correctly with the following information:3 1. Columns with titles for alcohol, carboxylic acid, Ester 2. Name of all alcohols, carboxylic acid and ester Alcohol Carboxylic acidEster MethanolEthanoic acidMethyl ethanoate Ethanol Propanoic acid Ethyl propanoate PropanolMethanoic acid Propyl methanoateAble to construct a table correctly with 2 esters named correctly 2Able to construct a table correctly with 1 ester named correctly1Wrong response or no response 0QuestionRubric Score2(c)Able to name the alcohol and carboxylic acid correctly.3Alcohol: PropanolCarboxylic acid: Butanoic acidAble to name alcohol or carboxylic acid correctly 2Able to name any alcohol or any carboxylic1Wrong response or no response 0Question RubricScore2(d)(i) Able to state the three variables correctly.3Sample answerManipulated variable: Hexane and hexeneResponding variable: Colour change of bromine water// colour change of potassium manganate (VII) solutionFixed variable: Bromine water//acidified potassium manganate(VII) solutionAble to state any two variable correctly 2Able to state any one variable correctly 1Wrong response or no response0QuestionRubric Score2(d)(ii)Able to state the hypothesis accurately3Sample answer:Hexane declourised the brown colour of bromine water, hexane does not//Hexane declourised the purple colour of acidified potassium manganate(VII)solution, hexane does notAble to state the hypothesis but less accurately2Sample answerBrown bromine water decolourised with hexene but no change with hexane.Able to state an idea of hypothesis 1No response or wrong response 0 37 38. QuestionRubricScore2(d)(iii) Able to state the operational definition accurately 3Sample answerWhen bromine water //acidified potassium manganate(VII) solution isadded to hexane/alkene brown bromine water //purple colour potassiummanganate(VII) solution decolourisedAble to state the operational definition less accurately2Sample answerAlkene decolourised brown bromine water//Alkene decolourised purplecolour potassium manganate(VII) solutionAble to state an idea of operational definition 1Alkene decolourised bromine water//acidified potassium manganate(VII)solutionNo response or wrong response 0 Question Rubric Score2(d)(iv)Able to predict and make explainations accurately 3Answer 1. Hexene 2. Percentage of carbon atoms per molecule hexene is higher thanhexaneAble to give anyone of the above answer 2Able to give an idea of prediction/explanation1Alkene//more carbon atomsNo response or wrong response 0QuestionRubric Score3(a) Able to state the aim accurately Sample answer2 To compare the effectiveness of cleaning agents A and B on cleansing action in hard water . Able to state the problem statement less accurately1 Sample answer Cleansing action of cleaning agent B is more effective No response or wrong response0Question RubricScore3(b) Able to state the three variables accurately. 3 Answer Manipulated variable: Celaning agent A and B Responding variable: Effectiveness of cleansing action Fixed variable: Type of water//hard water Able to state any two variables accurately 2 Able to state any one variable accurately1 No response or wrong response0Question RubricScore3(c) Able to state the hypothesis accurately with direction3 Sample answerCleaning agent B is more effective than clening agent A in hard waterAble to state the hypothesis less accurately2Sample answerCleansing action of cleaning agent B is better /more effective38 39. Able to state an idea of hypothesis1 Sample answer Cleansing action in hard water No response of wrong response0Question Rubric Score3(d) Able to state the complete list of apparatus and material as follows 3 Hard water, cleaning agent A and B,2 beakers, 2 pieces of cloths stained with oil, galss rod Able to state a list of apparatus and materials as follows 2 Hard water, cleaning agent A and B, 2 beakers, 2 pieces of cloths stained with oil, Able state one apparatus one material1 No response or wrong response0Question Rubric Score3(e) Able to state procedures correctly as follows31. [50 - 200] cm3 of hard water is poured into a beaker2. Cleaning agent A is added into the beaker3. A piece of cloth stained with oil is immersed in the solution4. The cloth is shaken/rubbed/stirred5. Observation is recorded6. Repeat steps 1 5 by using cleaning B . Able to state steps 2, 3, 5 and 62 Able to state steps 2 and 31 No response or wrong response0Question Rubric Score3(f) Able to tabulate the data correctly Sample answer3Type of cleaning agentrObservationCleaning agent ACleaning agent AType of cleaning agentrObservation2 Able to give an idea of tabulation of data 1 No response or wrong response0Marking Scheme Paper 3 Set 3Question Rubric Score1(a)(i)Able to record the thermometer reading accurately to 1 decimal place 3 with unit. Answer Initial temperature = 30.0 oC Highest temperature = 60.0 oC Able to record the thermometer reading correctly without unit2 Sample answer: Initial temperature = 3039 40. Highest temperature = 60 Able to record one thermometer reading correctly1 Sample answer 30 // 60 No response or wrong answer 0(a)(ii)Able to state one observation accurately3 Sample answer Thermometer reading increases//Temperature increases Able to state the observation less accurately 2 Sample answer Temperature reading increases/higher//Temperature rises Able to state the idea of observation 1 Sample answer Thermometer reading change//Temperature change Wrong or no response0(a)(iii) Able to state the inference accurately. 3 Sample answer Heat energy is released //The reaction is exothermic reaction Able to state the inference correctly 2 Sample answer Heat energy is absorbed by water Able to state an idea of inference1 Temperature of water increases Wrong or no response0(b)(i) Able to state all the mass of alcohols accurately to 2 decimal places 3 with unit Answers 1.55g, 2.23g, 3.56g, 4.01g Able to state at least 3 mass of alcohols accurately or 4 mass of alcohol 2 correctly to 4 decimal places Answer 1.5536, 2.2309, 3.5601, 4.0101 Able to state at least 2 mass of alcohol correctly1 Wrong or no response0(b)(ii)Able to tabulate the initial mass, final mass and mass of alcohols3 accurately with units Sample answer:Alcohol Initial mass/gFinal mass/gMass ofalcohol/gMethanol354.9548353.40121.55Ethanol 342.0201339.78922.23Propanol364.4303360.87023.56Butanol 332.9891328.97904.01 Able to tabulate the initial mass, final mass and mass of alcohols2 correctly without unit Able to tabulate at least 2 readings of the initial mass, final mass and1 mass of alcohols with correctly Wrong or no response0 40 41. (c) Able to calculate the heat of combustion of methanol correctly with the 3following steps:1. Heat change = 200 x 4.2 x 30 J= 25200 J2. No of mole of methanol = 1.55 16= 0.13. Heat of combustion = - 252 kJ mol-1Able to calculate with at least 2 steps correctly 2Able to calculate at least 1 step correctly 1Wrong or no response0(d)(i)Able to state the variables correctly 3Sample answerManipulated variableType of alcohols// Methanol, Ethanol, Propanol, ButanolResponding variableHeat of combustionFixed variableVolume of waterAble to state any two variables correctly 2Able to state any one variable correctly1Wrong or no response0(d)(ii) Able to state the hypothesis accurately with the manipulated variable 3related to responding variableSample answerWhen the number of carbon atoms per molecule alcohol increases, theheat of combustion increasesAble to state the hypothesis correctly with RV to MV2Sample answerHeat of combustion increases when the number of carbon atoms permolecule increasesAble to state an idea of hypothesis.1Sample answerHeat of combustion is different for different alcoholWrong or no response(e) Able to predict the heat of combustion for pentanol correctly 3Sample answer2350 kJ mol-1// (2300 2400)kJ mol-1Able to give the heat of combustion with the following value2Sample answerMore than 1860 kJ mol-1Able to give an idea to predict a value of heat of combustion:1 more than 2350 kJ mol-1Wrong or no response041 42. (f)Able to state the operational definition of heat of combustion of methanol3 in this experiment correctly Sample answer When 1 mole of ethanol is burnt to heat 200 cm3 of water, 252 kJ of heat energy is released Able to state the operational definition but less accurately2 Sample answer When 1 mole of ethanol is burnt, 252 kJ of heat energy is released Able to state an idea of operational definition 1 Sample answer When ethanol is burnt heat energy is relaeased Wrong or no response0(g)Able to state the three reasons correctly 3 Sample answer1. Some of the heat energy is released to the surrounding2. Some of the heat energy is absorbed by the copper can3. Incomplete combustion of ethanol Able to state any two reasons correctly 2 Able to state any one reason correctly1 Wrong or no response0(h)Able to classify all the compounds correctly3 Sample answerHydrocarbonNon-hydrocarbonHexene Propanoic acidMethaneEthanol Able to classify at least three compounds correctly 2 Able to classify at least two compounds correctly 1 Wrong or no response0Question 22(a) Able to state the aim of experiment accurately2 Sample answer To determine the effect of type of electrode on the selection of ions to be discharged at the anode/ on the product formed at the anode. Able to state the aim of experiment less accurately 1 Sample answer To determine type of electrode affects the product formed at the anode Wrong or no response02(b) Able to state all the variables 3 Sample answer Manipulated variable Type of electrodes//Carbon electrodes and copper electrodes Responding variable Product formed at anode Fixed variable Electrolyte Able to state any two variables correctly 2 Able to state any one variable1 Wrong or no response0 42 43. 2(c) Able to state the hypothesis accurately3 Sample answer When carbon electrodes are used, bubbles/oxygen gas released at anode, when copper electrodes are used, anode becomes thinner/ionised Able to state the hypothesis less accurately 2 Sample answer When different type of electrodes are used, different product is formed at the anode Able to state an idea of hypothesis1 Sample answer Type of electrodes affect products formed Wrong or no response 02(d) Able to list completely the materials and apparatus as the following 3 Copper(II) sulphate solution (0.5 2.0) mol dm-3, copper rods, carbon rods, electrolytic cell, battery, connecting wires, test tube Able to list the following apparatus and materials:2Copper(II) sulphate solution, carbon rods/ copper rods, beaker, battery, connecting wire Able to give at least one material, one apparatus1 Copper(II) sulphate solution//carbon rods//copper rods Beaker Wrong or no response 02(e) Able to state the all the following procedures 31. Half filled the electrolytic cell/beaker with copper(II) sulphate solution2. A test tube filled with copper(II) sulphate solution is inverted over the anode carbon electrode3. Both electrodes are connected to the batteries using connecting wires//Complete the circuit4. Record the observations at the anode5. Repeat steps 1-4 by using copper electrodes Able to state steps 1, 3, 4 and 52 Able to state steps 1 and 31 Wrong or no response 02(f) Able to draw a table for tabulation of data correctly with the following3Type of electrodesObservation at anodeCarbonCopper Able to draw a table with the following 2Type of electrodesObservationType of electrodes 1 Wrong or no response0 END OF MARKING SCHEME43