Physical Sciences Grade 12 P2 Eastern Cape June 2021 QP

NATIONAL SENIOR CERTIFICATE GRADE 12 JUNE 2021 PHYSICAL SCIENCES: CHEMISTRY (P2) (EXEMPLAR) MARKS: 150 TIME: 3 hours This question paper consists of 20 pages, including 2 data sheets.

2 PHYSICAL SCIENCES P2 (EC/JUNE 2021) INSTRUCTIONS AND INFORMATION 1. Write your name and surname in the appropriate space on the ANSWER BOOK. 2. This question paper consists of SEVEN questions. Answer ALL the questions in the ANSWER BOOK. 3. Start EACH question on a NEW page in the ANSWER BOOK. 4. Number the answers correctly according to the numbering system used in this question paper. 5. Leave ONE line between two subquestions, for example between QUESTION 2.1 and QUESTION 2.2. 6. You may use a non-programmable calculator. 7. You may use appropriate mathematical instruments. 8. You are advised to use the attached DATA SHEETS. 9. Show ALL formulae and substitutions in ALL calculations. 10. Round off your FINAL numerical answers to a minimum of TWO decimal places. 11. Give brief motivations, discussions, et cetera where required. 12. Write neatly and legibly. Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 3 QUESTION 1: MULTIPLE-CHOICE QUESTIONS Various options are provided as possible answers to the following questions. Choose the answer and write only the letter (A–D) next to the question numbers (1.1–1.10) in the ANSWER BOOK, for example 1.11 E. 1.1 The general formula for ALKANES is … A CnH2n. B CnH2n-1. C CnH2n-2. D CnH2n+2. (2) 1.2 The following graph shows the relationship between the number of carbon atoms in a straight chain molecules of alkanes, alcohols and aldehydes. Curves P, Q and R is obtained. Curve R Curve Q Curve P Boiling point (K) Number of C atoms Which ONE of the following CORRECTLY describes the homologous series against the curve? Curve P Curve Q Curve R A Alcohols Aldehydes Alkanes B Aldehydes Alcohols Alkanes C Alcohols Alkanes Aldehydes D Alkanes Aldehydes Alcohols (2) Copyright reserved Please turn over

4 PHYSICAL SCIENCES P2 (EC/JUNE 2021) 1.3 An alkene reacts with an EXCESS amount of water in the presence of an acid catalyst to produce compound P as shown in the equation below. ALKENE + H2O → compound P Compound P is a(n) … A alcohol. B alkane. C haloalkane. D carboxylic acid. (2) 1.4 Activation energy of a chemical reaction is defined as: A Net energy released B Net energy absorbed C Minimum energy needed to start the reaction D Maximum energy needed to start the reaction (2) Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 5 1.5 Consider the potential energy diagram for a reversible hypothetical reaction represented by the balanced equation below. X2(g) ⇌ 2X(g) POTENTIAL ENERGY DIAGRAM E1 Potential Energy (kJ/mol) E1 E2 0 Course of reaction E1 and E2 are the activation energies for the forward and reverse reactions respectively. The difference (E2 – E1) is equal to … A energy of the product. B ΔH for the forward reaction. C ΔH for the reverse reaction. D energy of the activated complex. (2) 1.6 A chemical reaction reaches chemical equilibrium in a closed system. At equilibrium concentration of products and reactants remains constant because the rate of the forward reaction is … A zero. B higher than the rate of the reverse reaction. C lower than the rate of the reverse reaction. D equal to the rate of the reverse reaction. (2) Copyright reserved Please turn over

6 PHYSICAL SCIENCES P2 (EC/JUNE 2021) 1.7 Consider the following reaction at equilibrium in a closed system. Cu(H2O)62+ (aq) + 4 Cℓ- (aq) ⇋ CuCℓ42- (aq) + 6 H2O (ℓ) ΔH > 0 BLUE GREEN Which ONE of the following changes to the equilibrium mixture above will ensure a COLOUR change from GREEN to BLUE? A Increase in pressure B Addition of silver nitrate C Increase in temperature D Addition of hydrochloric acid (2) 1.8 The endpoint in a titration is the exact point where … A neutralisation occurs. B the indicator changes colour. C equal masses of base and acid have reacted. D equal number of moles of acid and base have reacted. (2) 1.9 In the table below the ionisation constant values for bases, Kb at 25 °C are given. Which ONE of the following bases is the STRONGEST? BASE Kb at 25 °C A SO42- 8,3 x 10 -13 B PO43- 5,9 x 10-3 C HCO3- 2,4 x 10 -8 D CH3COO- 5,6 x 10 -10 (2) Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 7 1.10 Water undergoes auto-ionisation according to the balanced equation: H2O(ℓ) + H2O(ℓ) ⇋ H3O+ (aq) + OH- (aq) ΔH > 0 The ionisation constant Kw for water is 1,00 x 10 -14 at 25 °C Which ONE of the following is TRUE when the temperature of water in a beaker is increased from 25 °C to 30 °C? A Kw remains the same and the water becomes acidic B Kw remains the same and the water remains neutral C Kw increases and the water remains neutral D Kw decreases and the water remains neutral (2) [20] Copyright reserved Please turn over

8 PHYSICAL SCIENCES P2 (EC/JUNE 2021) QUESTION 2 (Start on a new page.) 2.1 The compound P, shown below, belongs to alkynes which is a group of organic compounds with the same general formula and functional group. H CH2CH3 H C CH C C CH2 CH3 CH3 CH3 2.1.1 Write down a general term for the underlined phrase. (1) 2.1.2 Is compound P a SATURATED or UNSATURATED compound? Give a reason for the answer. (2) For compound P write down the: 2.1.3 Empirical formula (1) 2.1.4 IUPAC name (3) 2.2 Consider compounds A and B given below. A: propan-1-ol B: HCOOH 2.2.1 Write down the STRUCTURAL formula of compound A. (2) Compounds A and B are heated together in the presence of a catalyst in a test tube to produce an ESTER. 2.2.2 Describe how the mixture of A and B in the test tube is heated. (2) For the reaction between compounds A and B write down the: 2.2.3 Name of the reaction taking place (1) 2.2.4 Formula of the catalyst used (1) 2.2.5 STRUCTURAL formula of the ester that is produced (2) Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 9 2.3 Haloalkanes, compounds C, D and E are structural isomers. Compounds C and D are shown below and compound E is not shown: C: CH3CH2CH2CH2Br D: (CH3)3CBr 2.3.1 Define the term structural isomer. (2) 2.3.2 Give a reason why compound C is classified as a PRIMARY haloalkane. (2) 2.3.3 Write down the IUPAC name of compound E, the POSITIONAL isomer of compound D. (3) [22] Copyright reserved Please turn over

10 PHYSICAL SCIENCES P2 (EC/JUNE 2021) QUESTION 3 (Start on a new page.) A group of learners investigated the effect of intermolecular forces on the boiling points of compounds. They tabulated their results below: Compounds Boiling point (°C) A Propan-1-ol 97 B Butan-1-ol 117,7 C Pentan-1-ol 138 3.1 Define the term boiling point. (2) 3.2 Which compound (A, B or C) will have the highest vapour pressure at a given temperature? Refer to the data in the table to explain the answer. (2) 3.3 For this investigation, write down the: 3.3.1 Independent variable (1) 3.3.2 Controlled variable (1) 3.4 Explain the trend in boiling point in the table above by referring to the MOLECULAR STRUCTURE, INTERMOLECULAR FORCES and ENERGY involved. (4) 3.5 The compound, 2-methylpropan-1-ol is a CHAIN ISOMER of one of the compounds in table. 3.5.1 Write down the structural formula for 2-methylpropan-1-ol. (2) 3.5.2 Which compound (A, B, or C) in the table above is a CHAIN ISOMER of 2-methylpropan-1-ol? Give a reason for the answer. (2) 3.5.3 How will the boiling point of 2-methylpropan-1-ol compare to the isomer named in QUESTION 3.5.2? Write only HIGHER THAN, LOWER THAN or EQUAL TO. (1) 3.5.4 Explain the answer to QUESTION 3.5.3 by referring to the MOLECULAR STRUCTURE, INTERMOLECULAR FORCES and ENERGY involved. (3) Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 11 3.6 Methanoic acid is a smaller compound than propan-1-ol. The boiling point of methanoic acid is HIGHER than propan-1-ol. Fully explain why the boiling point of methanoic acid is higher than propan-1-ol. Refer to the TYPE OF INTERMOLECULAR FORCES and energy involved. (4) [22] Copyright reserved Please turn over

12 PHYSICAL SCIENCES P2 (EC/JUNE 2021) QUESTION 4 (Start on a new page.) Hexane undergoes thermal cracking according to the balanced equation below. C6H14 Alkane X + C2H4 4.1 Define cracking. (2) 4.2 Write down the: 4.2.1 Molecular formula of alkane X (2) 4.2.2 One reaction condition (1) The alkane X, produced in the cracking reaction above, is used to produce other organic compounds as shown in the flow diagram below. The numbers I, II and III represent organic reactions. Alkane X I 2-bromobutane II III Alkene (Major product) 4.3 Write down the TYPE of reaction represented by: 4.3.1 I (1) 4.3.2 II (1) 4.4 Write down the NAME of the type of addition reaction represented by reaction III. (1) 4.5 Write down the NAME or FORMULA of the: 4.5.1 Inorganic reactant used in reaction I (1) 4.5.2 Catalyst used in reaction III (1) 4.6 Write down a balanced equation using CONDENSED structural formulae of organic reagents for reaction II. (5) [15] Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 13 QUESTION 5 (Start on a new page.) A group of learners conduct experiments to investigate a factor that affects the rate of reactions. In the experiments, the learners use the reaction between zinc granules and EXCESS hydrochloric acid of concentration 0,5 mol∙dm-3 at 20 °C as shown below: Experiment A: Zn (s) + 2 HCℓ (aq) → ZnCℓ2 (aq) + H2 (g) ΔH < 0 5.1 Define reaction rate. (2) 5.2 Is net energy ABSORBED or RELEASED during the reaction? Give a reason for the answer. (2) 5.3 How will the rate of reaction in experiment A be affected by the following changes? Choose from INCREASES, DECREASES or NO EFFECT. 5.3.1 Using H2SO4 solution of concentration 0,5 mol∙dm-3 in place of the HCℓ. (1) 5.3.2 Pressure is increased. (1) Copyright reserved Please turn over

14 PHYSICAL SCIENCES P2 (EC/JUNE 2021) 5.4 In experiment A, 50 cm3 of hydrochloric acid (HCℓ) solution of concentration 0,5 mol∙dm-3 reacts with 7,15 g of zinc (Zn) granules. The volume gas formed versus time for the reaction in experiment A is shown below. GRAPH OF VOLUME OF H2 VERSUS TIME 300 200 Volume of H2 gas (cm3) 100 0 30 60 90 120 150 180 210 240 Time (s) 5.4.1 How many seconds did the reaction take to reach completion? (1) It is observed that the rate of reaction is HIGHEST during the interval 0 to 30 s. 5.4.2 Write down TWO factors that influence reaction rate that explains this observation. (2) 5.5 Calculate the: 5.5.1 Average rate of reaction (in cm3∙s-1) for the first 120 s (3) 5.5.2 Mass of the EXCESS reactant remaining in the flask if the molar volume of hydrogen gas at 20 °C is 24 dm3∙mol-1 (7) Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 15 5.6 In experiment B, the reaction in experiment A is repeated under the same conditions, but copper is also added to the reaction mixture. Cu Experiment B: Zn (s) + HCℓ (aq) → ZnCℓ2 (aq) + H2 (g) The Maxwell-Boltzman distribution curve for the reaction in experiment A and in experiment B is shown below: Number of particles EB EA EA and EB represent the activation energy for the reaction in experiments A and B respectively. 5.6.1 What is the function of copper in experiment B? (1) 5.6.2 Explain how the addition of copper in reaction B affects the rate of reaction by referring to the collision theory. (4) [24] Copyright reserved Please turn over

16 PHYSICAL SCIENCES P2 (EC/JUNE 2021) QUESTION 6 (Start on a new page.) The reversible reaction given below reaches equilibrium at 350 °C in a closed container. N2(g) + 3 H2(g) ⇋ 2 NH3(g) ΔH < 0 6.1 Define the term reversible reaction. (2) 6.2 The temperature of the equilibrium mixture is decreased. How will the decrease in temperature affect the following? Choose from INCREASES, DECREASES or REMAINS CONSTANT. 6.2.1 Rate of the forward reaction (1) 6.2.2 Number of moles of NH3 at equilibrium (1) 6.3 Explain the answer to QUESTION 6.2.2 above by referring to Le Chatelier’s principle. (2) 6.4 The reaction is started by placing 7,84 grams of N2 and 0,6 moles of H2 in an empty flask which is then sealed. When equilibrium is reached at 350 °C the amount of NH3 present is 0,12 moles. The volume of the container is 2 dm3. Calculate the value of the equilibrium constant at 350 °C. (8) Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 17 The graph shown below shows the percentage yield of NH3 at 350 °C at different pressure values. GRAPH OF PERCENTAGE YIELD VS PRESSURE 60 350 °C Percentage yield of NH3 40 20 100 200 300 400 Pressure (atmospheres) 6.5 Write down a CONCLUSION that can be drawn from the graph about the relationship between percentage yield of NH3 and pressure at constant temperature. (2) 6.6 Use information from QUESTION 6.4 and the graph to determine the pressure at which the reaction reached equilibrium. (5) [21] Copyright reserved Please turn over

18 PHYSICAL SCIENCES P2 (EC/JUNE 2021) QUESTION 7 (Start on a new page.) 7.1 Sodium carbonate ionises in water into sodium ions (Na+) and carbonate ions (CO32-). Carbonate ions in solution undergo hydrolysis according to the balanced equation: CO32- (aq) + H2O (ℓ) ⇋ HCO3- (aq) + OH- (aq) 7.1.1 Define hydrolysis. (2) 7.1.2 Give a reason why a solution of sodium carbonate in water is alkaline by referring to substance(s) in the equation above. (2) 7.1.3 Write down the FORMULAE of the TWO acids in the equation. (2) 7.1.4 Give a reason why HCO3- can act as an ampholyte. (2) 7.2 A solution of a strong diprotic acid X has pH = 1. 7.2.1 Define an acid according to the Lowry-Bronsted theory. (2) 7.2.2 Calculate the concentration of acid X. (4) A solution of acid X of concentration 0,049 mol.dm-3 is diluted by adding 15 cm3 of the acid to water to produce 90 cm3 of a dilute standard solution. 7.2.3 Explain the meaning of the term standard solution. (2) The DILUTE solution of acid X is titrated with a solution of potassium hydroxide. The following list of indicators are available for the titration. Indicator pH-range Methyl orange 3,1 – 4,4 Bromothymol blue 6,0 – 7,6 Phenolphthalein 8,3 – 10,0 7.2.4 Which ONE of the indicators is the most suitable for this titration? Explain the answer. (3) During the titration 25 cm3 of the DILUTE acid X solution neutralises exactly 28,5 cm3 of a potassium hydroxide solution. 7.2.5 Calculate the concentration of the potassium hydroxide solution. (7) [26] TOTAL: 150 Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 19 NATIONAL SENIOR CERTIFICATE NASIONALE SENIOR SERTIFIKAAT 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 Standard pressure Standaarddruk p 1,013 x 105 Pa Molar gas volume at STP Molêre gasvolume teen STD Vm 22,4 dm3∙mol-1 Standard temperature Standaardtemperatuur Tθ 273 K Charge on electron Lading op elektron e -1,6 x 10-19 C Avogadro’s constant NA 6,02 x 1023 mol-1 Avogadro se konstante TABLE 2: FORMULAE/TABEL 2: FORMULES m n= M or/of n m c = V or/of c = MV pH= -log[H3O+] N n= or/of NA ca Va na Kw = [H3O+][OH-] = 1x10-14 = V cb Vb nb n= V at/by 298 K o Eθcell = Eθcathode – Eθanode / Eθsel = Eθkatode – Eθanode Eθcell = Eθreduction – Eθoxidation / Eθsel = Eθreduksie – Eθoksidasie Eθcell = Eθoxidising agent – Eθreducing agent / Eθsel = Eθoksideermiddel – Eθreduseermiddel Copyright reserved Please turn over

(EC/JUNE 2021) PHYSICAL SCIENCES P2 20 TABLE 3: THE PERIODIC TABLE OF ELEMENTS/TABEL 3: DIE PERIODIEKE TABEL VAN ELEMENTE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 (I) (II) Atoomgetal (III) (IV) (V) (VI) (VII) (VIII) KEY/ SLEUTEL 1 Atomic number 2 2,1 H He 1 29 4 3 4 Elektronegatiwiteit Simbool 5 6 7 8 9 10 1,0 1,5 1,9 2,0 2,5 3,0 3,5 4,0 Li Be Electronegativity Cu Symbol B C N O F Ne 7 9 11 12 14 16 19 20 11 12 63,5 13 14 15 16 17 18 0,9 Na 1,2 Mg 1,5 Aℓ 1,8 Si 2,1 P 2,5 S 3,0 Cℓ Ar Benaderde relatiewe atoommassa 23 24 27 28 31 32 35,5 40 19 20 21 22 23 24 25 26 relative Approximate 27 atomic 28 mass29 30 31 32 33 34 35 36 0,8 K 1,0 Ca 1,3 Sc 1,5Ti 1,6 V 1,6 Cr 1,5Mn 1,8 Fe Co 1,8 Ni Cu 1,8 1,9 1,6 Zn 1,6 Ga 1,8 Ge 2,0 As 2,4 Se 2,8 Br Kr 39 40 45 48 51 52 55 56 59 59 63,5 65 70 73 75 79 80 84 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 0,8 Rb 1,0 Sr 1,2 Y 1,4Zr Nb 1,8 Mo 1,9Tc 2,2 Ru Rh 2,2 Pd Ag 2,2 1,9 1,7 Cd 1,7 In 1,8 Sn 1,9 Sb 2,1 Te 2,5 I Xe 86 88 89 91 92 96 101 103 106 108 112 115 119 122 128 127 131 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 0,7 Cs 0,9 Ba La 1,6Hf Ta W Re Os Ir Pt Au Hg 1,8 Tℓ 1,8 Pb 1,9 Bi 2,0 Po 2,5 At Rn 133 137 139 179 181 184 186 190 192 195 197 201 204 207 209 87 88 89 0,7 Fr 0,9 Ra Ac 226 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 140 141 144 150 152 157 159 163 165 167 169 173 175 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr 232 238 Copyright reserved