Physical Sciences Grade 12 P2 Limpopo November 2014 QP (Eng)

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 12 PHYSICAL SCIENCES: CHEMISTRY (P2) PREPARATORY EXAMINATIONS SEPTEMBER 2014 MARKS: 150 TIME: 3 hours This question paper consists of 14 pages and 4 data sheets. Copyright reserved

Downloaded from hlayiso.com Physical Sciences/P2 2 LimpopoDoE/September 2014 CAPS INSTRUCTIONS AND INFORMATION 1. Write your NAME in the appropriate space on the ANSWER BOOK. 2. This question paper consists of TEN questions. Answer ALL the questions in the ANSWER BOOK. 3. Start EACH question at the top of a NEW page in the ANSWER BOOK. 4. You may use a non-programmable calculator. 5. You may use appropriate mathematical instruments. 6. YOU ARE ADVISED TO USE THE ATTACHED DATA SHEETS. 7. Number the answers correctly according to the numbering system used in this question paper. 8. Give brief motivations, discussions, et cetera where required. 9 Round off your final numerical answers to a minimum of TWO decimal places. 10 Write neatly and legibly Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 3 LimpopoDoE/September 2014 CAPS QUESTION 1: MULTIPLE-CHOICE QUESTIONS Four options are provided as possible answers to the following questions. Each question has only ONE correct answer. Write only the letter (A–D) next to the question number (1.1–1.10) in the ANSWER BOOK. 1.1 CnH2n+1OH is the GENERAL FORMULA for … A Alkanes. B Aldehydes. C Alcohols. D Alkenes. (2) 1.2 Consider the structural formula of an organic compound below. H H H C C O H Which ONE of the following is the correct IUPAC name of this compound? A Ethanone B Ethene. C Ethanol D Ethanal. (2) 1.3 Which ONE of the following reaction types can be used to prepare ETHENE from ETHANE? A Hydrogenation B Substitution C Dehydrogenation D Addition (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 4 LimpopoDoE/September 2014 CAPS 1.4 Two different metal blocks, X and Y, are fastened together with a plastic strip and placed in dilute hydrochloric acid solution. For which ONE of the combinations of X and Y shown in the table below will block X corrode faster than block Y? METAL X METAL Y A Iron (Fe) Tin (Sn) B Lead (Pb) Zinc (Zn) C Iron (Fe) Magnesium (Mg) D Lead (Pb) Magnesium (Mg) (2) 1.5 change in concentrat ion If P = , then P probably represents the … change in time A rate of reaction. B yield of products. C equilibrium constant. D pressure on the system. (2) 1.6 The equilibrium reaction, represented by the equation below, occurs at 25oC. 2NO2(g) N2O4(g) Which ONE of the following graphs BEST represents the relationship between the CONCENTRATION of NO2(g) and N2O4(g) in this reaction? A B [N2O4] [N2O4] 0 [NO2] 0 [NO2] C D [N2O4] [N2O4] 0 [NO2] 0 [NO2] (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 5 LimpopoDoE/September 2014 CAPS 1.7 Which ONE of the following is TRUE if the ACIDITY of a solution INCREASES? [H3O+] pH A Increases Increases B Increases Decreases C Decreases Increases D Decreases Decreases (2) 1.8 Which ONE of the following salts will LOWER the pH of distilled water when it is added to the water? A NaCℓ B NH4Cℓ C Na2CO3 D CH3COONa (2) 1.9 An electrochemical cell is to be set up to plate a nickel object with silver. Which ONE of the combinations below CORRECTLY shows the metal used for the positive electrode and the electrolytic solution in the electrochemical cell? ELECTROLYTE METAL USED FOR SOLUTION POSITIVE ELECTRODE A Silver Silver nitrate B Silver Nickel sulphate C Nickel Silver nitrate D Nickel Nickel sulphate (2) 1.10 Which ONE of the following fertilisers provides the most nitrogen per mole of fertiliser? A Ammonium nitrate B Potassium nitrate C Sodium nitrate D Ammonium phosphate (2) [20] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 6 LimpopoDoE/September 2014 CAPS QUESTION 2 (Start on a new page.) The letters P to W in the table below represent eight organic compounds. O P CH3CH2CH(CH3)CH2CH2CH2OH Q H 3C CH2 CH2 C O CH2 CH3 Br Cl S R CH2CH2 H2C CH CH2 CH2 Cl H O H H T Hexane U H C C C H H H H H H V W H C C C O CH3CH2CO2H H H H 2.1 Write down the: 2.1.1 lLetter that represents a SECONDARY alcohol. (1) 2.1.2 . (1) 2.1.3 name of the homologous series to which compound V belongs. (1) 2.1.4 IUPAC name of compound R. (2) 2.1.5 NAME of the polymer formed from compound S, if compound S is the monomer of a certain organic compound. . (1) 2.1.6 balanced equation, using MOLECULAR FORMULAE, for the combustion of compound T in excess oxygen. (3) 2.1.7 IUPAC name of compound P (2) 2.1.8 general formula of the homologous series to which compound Q belongs. (1) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 7 LimpopoDoE/September 2014 CAPS A few drops of fresh reddish-brown bromine water are added to compound S in a test tube. 2.2 Describe what will be observed in the test tube. (1) 2.3 Use structural formulae to write down a balanced equation for the reaction that takes place in the test tube. (4) [17] QUESTION 3 (Start on a new page.) Two separate experiments are conducted to determine the boiling points of organic compounds from different homologous series, under the same conditions. The results obtained are shown in the table below. Experiment Organic compound Relative Boiling Point Molecular Mass (°C) P CH3F -78,3 I Q CH3Cℓ -24,1 R CH3Br 3,7 X CH3(CH2)2COOH 88.1 163 II Y CH3(CH2)3CH2OH 88.1 137 Z CH3(CH2)3CHO 88.1 103 3.1 Define the term homologous series. (2) 3.2 From the table, write down the IUPAC names of the TWO compounds that will be gaseous at -20oC. (2) 3.3 Describe the trend in the boiling points of the compounds in Experiment I. (2) 3.4 Explain the trend in QUESTION 3.3 above. Make reference to INTERMOLECULAR FORCES and ENERGY needed in your explanation. (3) Use the data for Experiment II to answer QUESTIONS 3.5-3.7. 3.5 Formulate an investigative question for the experiment. (2) 3.6 NAME a variable that was kept constant in this experiment. (1) 3.7 State the conclusion that can be drawn from the results of this experiment. (2) [14] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 8 LimpopoDoE/September 2014 CAPS QUESTION 4 (Start on a new page.) The flow diagram below shows the preparation of different organic compounds using propene (CH3CH = CH2) as starting material. Polymer Y SATURATED HYDROCARBON CH3CH=CH2 H2O P 2-bromopropane 4.1 NAME the process that converts the saturated hydrocarbon to propene. (1) 4.2 Use structural formulae to write down a balanced chemical equation for the reaction between propene and water to produce compound P. (4) 4.3 Write down the IUPAC name of compound P. (1) 4.4 Compound P can also be obtained from 2-bromopropane. Write down the: 4.4.1 type of reaction that converts 2-bromopropane to P (1) 4.4.2 conditions under which the conversion can occur. (2) 4.5 Write down the: 4.5.1 NAME of polymer Y (1) 4.5.2 TYPE OF polymerisation that produces Y. Choose from ADDITION or CONDENSATION (1) [11] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 9 LimpopoDoE/September 2014 CAPS QUESTION 5: (Start on a new page.) The arrangement below is being used to investigate the rate of reaction of calcium carbonate and an excess 1 mol·dm-3 solution of hydrochloric acid. The equation for the reaction is: CaCO3 (s) + HCℓ (aq) → CaCℓ2(aq) + H2O(ℓ) + CO2(g) 1 mol·dm-3 hydrochloric Gas bubbles acid solution Calcium carbonate (CaCO3) Balance The mass of gas produced is obtained by measuring the loss in mass of the flask and its contents at one-minute intervals and the results are displayed in the graph below. 4,4 Mass of CO2 (g) 3,9 1 2 3 4 5 6 7 8 Time (minutes) 5.1 Give a reason for the loss in mass. (1) 5.2 Calculate the AVERAGE RATE (in g·s-1) of this reaction during the first four (4) minutes. (3) 5.3 Write down the loss in mass of the flask and its contents after 8 minutes. (2) 5.4 Give a reason why the curve flattens out after 4 minutes. (1) 5.4 Use the graph and any other relevant information to calculate the mass of calcium carbonate that reacted. (6) [13] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 10 LimpopoDoE/September 2014 CAPS QUESTION 6 (Start on a new page.) A hypothetical reaction, taking place in a closed 1 dm3 container, has reached equilibrium. The reaction is represented by the equation below: 2A(g) + 3B(g) 2C(g); H<0 This equilibrium is considered dynamic. 6.1 Explain the term dynamic equilibrium. (2) 6.2 Give a reason why the forward reaction is exothermic. (1) 6.3 State what change must be made to the system to increase the yield of C. Use your knowledge of Le Chatelier’s principle to explain the answer. (4) Initially, 2 moles of A(g) and 4 moles of B(g) were present in the container. The temperature was maintained at 150°C, and at equilibrium it was found that 2,41 x 1023 molecules of A(g) were present. 6.4 Calculate the value of the equilibrium constant (KC) at 150 o C. (8) 6.5 The pressure on the system is decreased by increasing the volume of the reaction vessel at the same temperature. How will this change affect the value of KC? Write down only INCREASES, DECREASES or REMAINS THE SAME. (1) [16] QUESTION 7 (Start on a new page.) A bottle contains dilute sulphuric acid of unknown concentration. In order to determine the concentration of the acid, a learner titrates the acid against a standard solution of potassium hydroxide. The balanced equation for the reaction is: H2SO4(aq) + 2KOH(aq)
K2SO4(aq) + H2O(ℓ) 7.1 Define the term dilute acid. (2) 7.2 Calculate the: 7.2.1 mass of potassium hydroxide which that must be used to prepare 300 cm3 of a 0,2 mol·dm-3 KOH solution. (4) 7.2.2 pH of the 0,2 mol·dm-3 KOH solution. Assume that KOH dissociates completely in distilled water. (6) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 11 LimpopoDoE/September 2014 CAPS 7.3 A list of indicators and their associated pH ranges are shown in the table below. INDICATOR pH RANGE Methyl orange 2,9 – 4,0 Bromothymol blue 6,0 – 7,6 Phenolphthalein 8,3 – 10,0 Which ONE of the indicators could best be used for the titration described in QUESTION 7 above? Briefly explain your answer. (3) 7.4 During the titration she finds that exactly 15,0 cm3 of the KOH solution neutralises 20,0 cm3 of the H2SO4 solution. Calculate the concentration of the H2SO4 solution. (5) [20] QUESTION 8 (Start on a new page.) A grade 12 learner is given an assignment to arrange some metals according to their reducing ability. He sets up the electrochemical cell shown in the diagram below. 8.1 Write down the name of the component labelled R and give ONE function of this component. (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 12 LimpopoDoE/September 2014 CAPS The learner uses different metals as electrodes. He records the following results: COMBINATION ELECTRODE ELECTRODE VOLTMETER P Q READING (V) 1 Chromium Silver +0,3 2 Silver Zinc -0,7 3 Zinc Chromium +0,4 8.2 State a suitable HYPOTHESIS for this investigation. (2) 8.3 Give a possible reason why the voltmeter reading for the silver-zinc cell is negative. (2) 8.4 State a suitable conclusion for this experiment when the cell functions correctly. (2) 8.5 Consider the ZINC-CHROMIUM CELL represented by the notation below: Zn(s)/Zn2+(aq, 1 mol·dm-3)//Cr3+ ( aq, 1 mol·dm-3) /Cr(s) 8.5.1 Use the table of Standard Reduction Potentials to determine the initial potential difference (emf) of this cell under standard conditions. (4) 8.5.2 Is the reaction that occurs in this cell spontaneous? State only YES or NO. Give a reason for the answer. (2) 8.5.3 How will the initial voltmeter reading be affected if the concentration of the electrolyte in the Zn(s)/Zn2+(aq) half-cell is increased? Write down only INCREASES, DECREASES or REMAINS THE SAME. (2) 8.6 A learner sets up a zinc-chromium cell. The potential difference measured differs from the one calculated in QUESTION 8.5.1. Give TWO possible reasons for this difference in values. (2) [18] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 13 LimpopoDoE/September 2014 CAPS QUESTION 9 (Start on a new page.) High purity copper is obtained by electrolysis using a thin, pure copper cathode and an ACIDIFIED solution of copper (II) sulphate Mass of Cu deposited (g) - + B A CuSO4(aq) 0 I(A) impurities 9.1 At which electrode would pure copper be deposited? Write only A or B. (1) 9.2 State the relationship between the CURRENT (I) and the MASS DEPOSITED depicted by the graph. (1) 9.3 When a constant current flows for 1 hour, 32 g of pure copper is deposited at one of the electrodes. 9.3.1 Would the mass lost by the other electrode be LARGER THAN, SMALLER THAN or EQUAL TO 32 g? (1) 9.3.2 Calculate the number of moles of copper deposited. (2) 9.3.3 Use the answer to QUESTION 9.3.2 and any other relevant information to determine the average current required to deposit 32 g of copper. (5) [10] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 14 LimpopoDoE/September 2014 CAPS QUESTION 10 (Start on a new page.) The flow diagram below represents the processes used to manufacture fertilizer D. Both the Haber and the Contact processes are part of the total process. Air Nitrogen B D Haber Oxygen Hydrogen Process A Sulphur C Sulphuric Dioxide Acid Water Contact Process Each process uses air for ONE of the starting materials. 10.1 NAME the process used to obtain nitrogen industrially. (1) 10.2 Write down the CHEMICAL NAME or FORMULA of the compound represented by the LETTER: 10.2.1 B (1) 10.2.2 A (1) 10.2.3 D (1) 10.3 Write down the NAME or FORMULA of the catalyst used in the Contact Process. (1) 10.4 Write down the name of the primary nutrient found in compound D. (1) 10.5 Write down the balanced chemical equation for the reaction which leads to the formation of substance C. (3) 10.6 Give ONE reason why there is a continuous worldwide demand for fertilisers. (1) [10] GRAND TOTAL :150 Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 15 LimpopoDoE/September 2014 CAPS DATA FOR PHYSICAL SCIENCES GRADE 12 PAPER 2 (CHEMISTRY) GEGEWENS VIR FISIESE WETENSKAPPE GRAAD 12 VRAESTEL 2 (CHEMIE) TABLE 1: PHYSICAL CONSTANTS/TABEL 1: FISIESE KONSTANTES NAME/NAAM SYMBOL/SIMBOOL VALUE/WAARDE Avogadro's constant NA 6,02 x 1023 mol-1 Avogadro-konstante Standard pressure pθ 1,013 x 105 Pa Standaarddruk Molar gas volume at STP Vm 22,4 dm3·mol-1 Molêre gasvolume by STD Standard temperature Tθ 273 K Standaardtemperatuur Charge on electron e -1,6 x 10-19 C Lading op elektron TABLE 2: FORMULAE/TABEL 2: FORMULES m N n= n= M NA V n m n= c= or/of c= Vm V MV pH = -log[H3O+] Kw = [H3O+][OH-] = 1 x 10-14 at/by 298 K Eθcell = Eθcathode − E θanode / E θsel = E katode θ − E θanode or/of E θcell = E reduction θ − E θoxidation / E θsel = E reduksie θ − E θoksidasie or/of E θcell = E θoxidising agent − E reducing θ θ θ θ agent / E sel = E oksideermi ddel − E reduseermi ddel Q = ne Q = It Copyright reserved Please turn over

Physical Sciences/P2 Downloaded from hlayiso.com 16 TABLE 3: THE PERIODIC TABLE OF ELEMENTS Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 17 LimpopoDoE/September 2014 CAPS TABLE 4A: STANDARD REDUCTION POTENTIALS Half-reactions Eθ (V) F2(g) + 2e− ⇌ 2F− + 2,87 3+ Co + e − ⇌ Co2+ + 1,81 + − H2O2 + 2H +2e ⇌ 2H2O +1,77 − MnO 4 + 8H+ + 5e− ⇌ Mn2+ + 4H2O + 1,51 Cℓ2(g) + 2e− ⇌ 2Cℓ− + 1,36 2− 3+ Cr2O 7 + 14H+ + 6e− ⇌ 2Cr + 7H2O + 1,33 + − O2(g) + 4H + 4e ⇌ 2H2O + 1,23 MnO2 + 4H+ + 2e− ⇌ Mn2+ + 2H2O + 1,23 Pt2+ + 2e− ⇌ Pt + 1,20 Br2(ℓ) + 2e− ⇌ 2Br− + 1,07 − NO 3 + 4H+ + 3e− ⇌ NO(g) + 2H2O + 0,96 Increasing reducing ability/Toenemende reduserende vermoë 2+ − Hg + 2e ⇌ Hg(ℓ) + 0,85 Ag+ + e− ⇌ Ag + 0,80 Increasing oxidising ability/Toenemende oksiderende vermoë − NO 3 + 2H+ + e− ⇌ NO2(g) + H2O + 0,80 3+ − 2+ Fe + e ⇌ Fe + 0,77 O2(g) + 2H+ + 2e− ⇌ H2O2 + 0,68 I2 + 2e− ⇌ 2I− + 0,54 Cu+ + e− ⇌ Cu + 0,52 SO2 + 4H+ + 4e− ⇌ S + 2H2O + 0,45 2H2O + O2 + 4e− ⇌ 4OH− + 0,40 2+ − Cu + 2e ⇌ Cu + 0,34 2− SO 4 + 4H+ + 2e− ⇌ SO2(g) + 2H2O + 0,17 2+ − + Cu + e ⇌ Cu + 0,16 Sn4+ + 2e− ⇌ Sn2+ + 0,15 S + 2H+ + 2e− ⇌ H2S(g) + 0,14 2H+ + 2e− ⇌ H2(g) 0,00 Fe3+ + 3e− ⇌ Fe − 0,06 Pb2+ + 2e− ⇌ Pb − 0,13 Sn2+ + 2e− ⇌ Sn − 0,14 Ni2+ + 2e− ⇌ Ni − 0,27 2+ − Co + 2e ⇌ Co − 0,28 Cd2+ + 2e− ⇌ Cd − 0,40 Cr3+ + e− ⇌ Cr2+ − 0,41 Fe2+ + 2e− ⇌ Fe − 0,44 Cr3+ + 3e− ⇌ Cr − 0,74 Zn2+ + 2e− ⇌ Zn − 0,76 2H2O + 2e− ⇌ H2(g) + 2OH− − 0,83 Cr2+ + 2e− ⇌ Cr − 0,91 Mn2+ + 2e− ⇌ Mn − 1,18 Aℓ3+ + 3e− ⇌ Aℓ − 1,66 Mg2+ + 2e− ⇌ Mg − 2,36 Na+ + e− ⇌ Na − 2,71 Ca2+ + 2e− ⇌ Ca − 2,87 Sr2+ + 2e− ⇌ Sr − 2,89 2+ − Ba + 2e ⇌ Ba − 2,90 Cs+ + e- ⇌ Cs - 2,92 K+ + e− ⇌ K − 2,93 Li+ + e− ⇌ Li − 3,05 Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 18 LimpopoDoE/September 2014 CAPS TABLE 4B: STANDARD REDUCTION POTENTIALS Half-reactions Eθ (V) Li+ + e− ⇌ Li − 3,05 K+ + e− ⇌ K − 2,93 Cs+ + e− ⇌ Cs − 2,92 Ba2+ + 2e− Ba − 2,90 Increasing reducing ability/Toenemende reduserende vermoë ⇌ Sr2+ + 2e− ⇌ Sr − 2,89 Increasing oxidising ability/Toenemende oksiderende vermoë Ca2+ + 2e− ⇌ Ca − 2,87 Na+ + e− ⇌ Na − 2,71 Mg2+ + 2e− ⇌ Mg − 2,36 Aℓ3+ + 3e− ⇌ Aℓ − 1,66 2+ − Mn + 2e ⇌ Mn − 1,18 Cr2+ + 2e− ⇌ Cr − 0,91 2H2O + 2e− ⇌ H2(g) + 2OH− − 0,83 Zn2+ + 2e− ⇌ Zn − 0,76 Cr3+ + 3e− ⇌ Cr − 0,74 Fe2+ + 2e− ⇌ Fe − 0,44 Cr3+ + e− ⇌ Cr2+ − 0,41 Cd2+ + 2e− ⇌ Cd − 0,40 Co2+ + 2e− ⇌ Co − 0,28 Ni2+ + 2e− ⇌ Ni − 0,27 Sn2+ + 2e− ⇌ Sn − 0,14 Pb2+ + 2e− ⇌ Pb − 0,13 Fe3+ + 3e− ⇌ Fe − 0,06 2H+ + 2e− ⇌ H2(g) 0,00 S + 2H+ + 2e− ⇌ H2S(g) + 0,14 4+ − 2+ Sn + 2e ⇌ Sn + 0,15 Cu2+ + e− ⇌ Cu+ + 0,16 2− SO 4 + 4H+ + 2e− ⇌ SO2(g) + 2H2O + 0,17 2+ Cu + 2e− ⇌ Cu + 0,34 2H2O + O2 + 4e− ⇌ 4OH− + 0,40 + − SO2 + 4H + 4e ⇌ S + 2H2O + 0,45 Cu+ + e− ⇌ Cu + 0,52 I2 + 2e− ⇌ 2I− + 0,54 O2(g) + 2H+ + 2e− ⇌ H2O2 + 0,68 Fe3+ + e− ⇌ Fe2+ + 0,77 − NO 3 + 2H+ + e− ⇌ NO2(g) + H2O + 0,80 + − Ag + e ⇌ Ag + 0,80 Hg2+ + 2e− ⇌ Hg(ℓ) + 0,85 − NO 3 + 4H+ + 3e− ⇌ NO(g) + 2H2O + 0,96 Br2(ℓ) + 2e− ⇌ 2Br− + 1,07 2+ Pt + 2 e− ⇌ Pt + 1,20 + MnO2 + 4H + 2e − ⇌ Mn2+ + 2H2O + 1,23 O2(g) + 4H+ + 4e− ⇌ 2H2O + 1,23 2− Cr2O 7 + 14H+ + 6e− ⇌ 2Cr3+ + 7H2O + 1,33 Cℓ2(g) + 2e− ⇌ 2Cℓ− + 1,36 − 2+ MnO 4 + 8H+ + 5e− ⇌ Mn + 4H2O + 1,51 + − H2O2 + 2H +2 e ⇌ 2H2O +1,77 Co3+ + e− ⇌ Co2+ + 1,81 F2(g) + 2e− ⇌ 2F− + 2,87 Copyright reserved Please turn over