Physical Sciences Grade 12 P2 Gauteng Prelim 2024 QP (Eng)

Downloaded from hlayiso.com PREPARATORY EXAMINATION 2024 10842 PHYSICAL SCIENCES: CHEMISTRY (PAPER 2) TIME: 3 hours MARKS: 150 16 pages + 4 information sheets P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 2 (PAPER 2) 10842/24 INSTRUCTIONS AND INFORMATION 1. Write your name in the appropriate space on the ANSWER BOOK. 2. This question paper consists of NINE questions. Answer ALL the questions in the ANSWER BOOK. 3. Start EACH question on a NEW page. 4. Number the answers correctly according to the numbering system used in this question paper. 5. Leave ONE line between subquestions, e.g. 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, etc. where required. 12. Write neatly and legibly. P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 3 (PAPER 2) 10842/24 QUESTION 1: MULTIPLE-CHOICE QUESTIONS Four options are given as possible answers to the following questions. Each question has only ONE correct answer. Choose the answer and write only the letter (A – D) next to the question numbers (1.1 to 1.10) in the ANSWER BOOK, e.g. 1.11 D. 1.1 Consider the flow diagram below: H2 Propene Compound X Pt Compound X is: A Propyne B Propan-1-ol C Propane D Propan-2-ol (2) 1.2 Which of the following compounds has the highest vapour pressure? A Ethane B Propane C Butane D Pentane (2) 1.3 During the dehydration of butan-2-ol represented below, a major organic compound (Y) is formed. dehydration CH3CH2CH(OH)CH3 Y Which of the following is the correct condensed structural formula for compound Y? A CH3CH2CH2CH3 B CH3CHCHCH3 C CH3CH2CH(OH)CH3 D CH3CH2CHCH2 (2) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 4 (PAPER 2) 10842/24 1.4 The complete combustion of ONE MOLE of butane needs at least: A 18 mol O2 B 5 mol O2 C 7 mol O2 D 13 mol O2 (2) 1.5 The Maxwell-Boltzmann energy distribution curves below show the number of particles as a function of their kinetic energy, for a reaction at four different temperatures. The minimum kinetic energy needed for effective collisions to occur is represented by E. A Number of particles B C D E Kinetic energy Which of these curves represents the reaction with the highest rate? A Curve A B Curve B C Curve C D Curve D (2) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 5 (PAPER 2) 10842/24 1.6 The graph below shows the changes in X, Y and Z over time during a reaction. X Amount (mole) Y Z Time(s) Which of the following balanced chemical equations is correct for this reaction? A X + 3Y → Z B 4X + 2Y → Z C 5X + 3Y → 2Z D 2X + 3Y → 2Z (2) 1.7 HPO is an ampholyte. Which of the following pairs represents the conjugate acid and base of HPO ? CONJUGATE ACID CONJUGATE BASE A PO 3 4 H2PO 14 B H2PO 1 4 PO 34 C H2PO 1 4 H3PO4 D H2PO 2 4 PO 24 (2) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 6 (PAPER 2) 10842/24 1.8 If the concentration of a sulphuric acid solution is 1 x 10-3 mol·dm-3, what will the pH and [OH-] of the solution be, respectively? pH [OH-] (mol∙dm-3) A 2,7 1 x 10-11 B 2,7 5 x 10-12 C 3,0 5 x 10-12 D 3,0 1 x 10-11 (2) 1.9 Which of the following containers can be used to store an iron(II) sulphate solution? A Aℓ B Mg C Ni D Zn (2) 1.10 Consider the following reaction which takes place in a galvanic cell: 2Cr2+(aq) + Sn4+(aq) ⇌ 2Cr3+(aq) + Sn2+(aq) The net cell potential (in V) when this cell reaches equilibrium will be … A + 0,56. B 0,00. C – 0,26. D – 0,56. (2) [20] P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 7 (PAPER 2) 10842/24 QUESTION 2 (Start on a new page.) The letters A to F in the table below represent six organic compounds. A CH3CH2CH2CH3 B Butanal C D E F CxHyOz 2.1 Is compound A, a SATURATED or an UNSATURATED hydrocarbon? Give a reason for the answer. (2) 2.2 Write down the LETTER/S that represent(s) each of the following: 2.2.1 A ketone (1) 2.2.2 A haloalkane (1) 2.2.3 The two functional isomers (1) 2.3 Consider compound C: 2.3.1 Is compound C a PRIMARY, SECONDARY or TERTIARY alcohol? Give a reason for the answer. (2) 2.3.2 Write down the STRUCTURAL FORMULA and IUPAC name of a chain isomer of compound C. (2) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 8 (PAPER 2) 10842/24 2.4 Write down the: 2.4.1 IUPAC name for compound D (2) 2.4.2 NAME of the functional group of compound B (1) 2.5 A sample of compound F contains 40% C; 53,3% O and X% H. 2.5.1 If the molar mass is 60 g∙mol-1, calculate the MOLECULAR FORMULA of compound F. (4) 2.5.2 Write down the IUPAC names of the two organic compounds that will have this molecular formula. (2) [18] QUESTION 3 (Start on a new page.) The table below shows the boiling points of four organic compounds, represented by the letters A to D, of comparable molecular masses. COMPOUND IUPAC NAME MOLAR MASS BOILING POINT (g•mol -1) (°C) A 2,3-dimethylbutane 86 57,9 B Hexane 86 68,7 C Methyl propanoate 88 79,8 D Pentan-1-ol 88 X or Y 3.1 Compounds A and B are structural isomers. 3.1.1 Define the term structural isomers. (2) 3.1.2 The boiling point of compound B is higher than the boiling point of compound A. Explain the difference in the boiling points. (3) 3.2 Define the term vapour pressure. (2) 3.3 Which ONE of the compounds B or C, will have a higher vapour pressure? Give a reason for the answer. (2) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 9 (PAPER 2) 10842/24 3.4 Consider compounds C and D. 3.4.1 Will the boiling point of compound D be X = 75,5 °C OR Y = 135,5 °C? Write down only X or Y. (1) 3.4.2 Explain the answer to QUESTION 3.4.1. (3) [13] QUESTION 4 (Start on a new page.) Consider the following sequence of organic reactions labelled A to E. A (HBr) B CH3CHCH2 Compound X Alcohol Y C (Major product) D and CH3CH2CH3 Alcohol Z E (Minor product) CH3CH2CH2OOCCH2CH3 4.1 Write down the type of reaction that occurs at: 4.1.1 A (1) 4.1.2 C (1) 4.2 Write down the NAME or FORMULA of the catalyst for reaction D. (1) 4.3 Reaction B is a substitution reaction that takes place in the presence of water. Write down the: 4.3.1 Type of substitution reaction for B (1) 4.3.2 TWO other reaction conditions for this reaction (2) 4.3.3 IUPAC name of the major product Y (2) 4.4 Use the structural formulae to write a balance equation for reaction B, showing the formation of alcohol Y. (3) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 10 (PAPER 2) 10842/24 4.5 Reaction E is a reaction between minor product, alcohol Z and a carboxylic acid to form an ester. Write down the: 4.5.1 Name of this type of reaction (1) 4.5.2 Name of the inorganic compound formed during this reaction (1) 4.5.3 Name of the catalyst needed for this reaction (1) 4.5.4 IUPAC name for the functional isomer of the ester formed (2) 4.6 Draw the STRUCTURAL FORMULA of the functional group of the carboxylic acid. (1) [17] P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 11 (PAPER 2) 10842/24 QUESTION 5 (Start on a new page.) Learners are asked to investigate the rate at which 0,3 g of impure calcium carbonate will react with an excess of 1 mol∙dm-3 hydrochloric acid at room temperature to produce CO2 gas. The equation for the reaction is: CaCO3 (s) +2HCℓ (aq) → CaCℓ2(aq) + H2O(ℓ) + CO2(g) gas syringe reaction mixture The graph below represents the volume of CO2(g) produced at regular time intervals. Volume (cm3) Time(s) 5.1 Write down: 5.1.1 An investigative question for this experiment (2) 5.1.2 A controlled variable (1) 5.1.3 The dependent variable for this investigation (1) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 12 (PAPER 2) 10842/24 5.2 With reference to the graph, how will the rate of reaction between the time 0 s to 20 s compare with the reaction rate between time 30 s to 50 s? (1) 5.3 What conclusion can be drawn from the graph between the time 60 s and 70 s? (1) 5.4 Use the graph to calculate the mass of calcium carbonate that reacted. The molar volume is 24 dm3 at room temperature. (5) 5.5 Calculate the percentage purity of the calcium carbonate which reacted in the above reaction. (2) 5.6 The learners repeat their investigation by using 0,3 g of the same impure calcium carbonate but increased the concentration of hydrochloric acid to 2 mol∙dm-3. 5.6.1 How will the gradient of the graph change when the concentration of the acid is increased? (1) 5.6.2 Use the Collision Theory to explain how an increase in concentration affects the rate of reaction. (3) [17] QUESTION 6 (Start on a new page.) Potassium dichromate is formed when nitric acid is slowly added to a potassium chromate solution. The chromate ions (CrO ) in the solution reach equilibrium with the dichromate ions (Cr O ) according to the following balanced ionic equation: 2CrO (aq) + 2H (aq) ⇌ Cr O (aq) + H O(ℓ) Yellow Orange 6.1 Define the term chemical equilibrium. (2) 6.2 A concentrated nitric acid solution is now added to this reaction mixture. 6.2.1 What colour change will be observed in the mixture? Choose from MORE YELLOW or MORE ORANGE. (1) 6.2.2 Explain the answer to QUESTION 6.2.1 in terms of Le Chatelier’s principle. (3) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 13 (PAPER 2) 10842/24 6.3 When the temperature of the original reaction mixture is increased, it is observed that the colour of the mixture changes to yellow. 6.3.1 Is the forward reaction ENDOTHERMIC or EXOTHERMIC? (1) 6.3.2 Explain the answer to QUESTION 6.3.1 in terms of Le Chatelier’s principle. (3) 6.4 11 mol CrO (aq) and 𝐱 mol H (aq) are initially added together to make a 0,5 dm3 solution and allowed to react. When the reaction reaches equilibrium, the solution contains 9 mol∙dm-3 Cr O (aq). Calculate the initial mole of H (aq) placed in the container if the equilibrium constant is 0,09. (8) [18] QUESTION 7 (Start on a new page.) 7.1 A solution of carbonic acid has a pH of 4,2 and the following Ka value: K = 4,30 × 10 A solution of sulphuric acid has the following Ka value: K = 1,0 × 10 7.1.1 Calculate the concentration of the hydronium ions in the carbonic acid solution. (3) 7.1.2 How will the strength of the carbonic acid compare to that of sulphuric acid if both acids have a concentration of 0,02 mol∙dm-3? Write only that the carbonic acid is STRONGER THAN, WEAKER THAN or THE SAME AS sulphuric acid. Give a reason for the answer. (2) 7.2 A solution of vinegar can be neutralised with a solution of sodium hydroxide. The reaction takes place according to the following balanced equation: CH COOH(aq) + NaOH(aq) → CH COONa(aq) + H O(ℓ) The sodium acetate produced during this reaction can undergo hydrolysis. 7.2.1 Define the term hydrolysis. (1) 7.2.2 Will the pH of the sodium acetate solution be GREATER THAN or LESS THAN 7? (1) 7.2.3 Explain the answer to QUESTION 7.2.2 by referring to a balanced equation. (3) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 14 (PAPER 2) 10842/24 7.3 An unknown carbonate has a chemical formula of Y2CO3. A learner is asked to identify element Y. The learner adds 0,5865 g of the carbonate in a conical flask containing 25 cm3 hydrochloric acid solution with a concentration of 0,3 mol∙dm-3. The balanced equation for the reaction that takes place is: 2HCℓ(aq) + Y CO (aq) → 2YCℓ(aq) + CO (g) + H O (ℓ) The hydrochloric acid is in EXCESS. 7.3.1 Calculate the initial mole of hydrochloric acid in the conical flask. (3) Once the mixture has stopped fizzing, 15 cm3 of a 0,1 mol∙dm-3 NaOH(aq) is added to the mixture to neutralise any remaining hydrochloric acid. 7.3.2 Calculate the amount of hydrochloric acid (in mole) that reacted with the unknown carbonate. (4) 7.3.3 Identify element Y. Show ALL calculations. (5) [22] QUESTION 8 (Start on a new page.) 8.1 A galvanic cell is constructed as shown in the diagram below. V Ni(s) Cd(s) Ni (aq) Cd (aq) 8.1.1 Which electrode is cathode? Write only NICKEL or CADMIUM. (1) 8.1.2 Write down the equation for the oxidation half-reaction of this cell. (2) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 15 (PAPER 2) 10842/24 8.1.3 How will the reading on the voltmeter be affected if the concentration of the nickel ions is increased after the cell has reached equilibrium? Choose from INCREASE, DECREASE or REMAIN THE SAME. Give a reason for the answer. (2) 8.2 Consider the following standard electrochemical cell: Cu(s)|Cu (aq)(1mol ∙ dm ) ∥ Ag (aq)(1mol ∙ dm )|Ag(s) Initially each half cell contains 200 cm3 electrolyte. The cell is connected to a circuit and allowed to produce current until the concentration of the electrolyte in the cathode half-cell is reduced to 0,5 mol·dm-3. The cell is then disconnected. 8.2.1 Write a balanced equation for the net ionic cell reaction. (3) 8.2.2 Calculate the concentration of the electrolyte in the anode half-cell when the cell is disconnected. (7) [15] QUESTION 9 (Start on a new page.) Electrolysis is generally used in industry to produce chemicals through the decomposition of compounds.The simplified diagram below represents an electrolytic cell used in the electrolysis of a concentrated sodium chloride solution. GAS GAS Concentrated COMPOUND C sodium chloride SOLUTION D SOLUTION E POWER SOURCE 9.1 Define the term anode in terms of oxidation or reduction. (1) P.T.O.

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 16 (PAPER 2) 10842/24 9.2 Which electrode, X or Y, is connected to the positive terminal of the power source? Give a reason for the answer. (2) 9.3 Write down the NAME or CHEMICAL FORMULA of: 9.3.1 Gas A (1) 9.3.2 Compound C (1) 9.4 Write down the equation for the half-reaction that takes place at the cathode of the cell. (2) 9.5 Refer to the relative strength of the oxidising agents to explain the answer to QUESTION 9.4. (3) [10] TOTAL: 150 END

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 17 (PAPER 2) 10842/24 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 p 1,013 x 105 Pa Standaarddruk Molar gas volume at STP Vm 22,4 dm3∙mol-1 Molêre gasvolume by STD Standard temperature T 273 K Standaardtemperatuur Charge on electron qe -1,6 x 10-19 C Lading op elektron Avogadro’s constant NA 6,02×1023 Avogadro-konstante TABLE 2: FORMULAE/TABEL 2: FORMULES m N n n M NA n m V c or/of c  n V MV Vm ca Va n  a pH = -log[H3O+] cb Vb nb E θcell  E θcathode  E θanode / E θsel  E θkatode  E θanode E θcell  E reduction θ  E θoxidation / E θsel  E θreduksie  E θoksidasie E θcell  E θoxidising agent  E θreducing agent / E θsel  E θoksideermiddel  E θreduseermiddel

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 18 (PAPER 2) 10842/24

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 19 (PAPER 2) 10842/24 TABLE 4A: STANDARD REDUCTION POTENTIALS TABEL 4A: STANDAARD REDUKSIEPOTENSIALE Half-reactions/Halfreaksies E (V) F2(g) + 2e ⇌ 2F + 2,87 3+ Co + e  ⇌ Co2+ + 1,81 H2O2 + 2H+ +2e ⇌ 2H2O +1,77  MnO 4 + 8H+ + 5e ⇌ 2+ Mn + 4H2O + 1,51 Cℓ2(g) + 2e  ⇌ 2Cℓ  + 1,36 2 Cr2O 7 + 14H+ + 6e ⇌ 3+ 2Cr + 7H2O + 1,33 O2(g) + 4H+ + 4e ⇌ 2H2O + 1,23 MnO2 + 4H + 2e +  ⇌ Mn2+ + 2H2O + 1,23 2+ Pt + 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 Fe3+ + e ⇌ Fe2+ + 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 Cu2+ + 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 Co2+ + 2e ⇌ Co  0,28 Cd2+ + 2e ⇌ Cd  0,40 Cr3+ + e ⇌ Cr2+  0,41 2+ Fe + 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 Ba2+ + 2e ⇌ Ba  2,90 Cs+ + e- ⇌ Cs – 2,92 K+ + e ⇌ K  2,93 + Li + e  ⇌ Li  3,05

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY 20 (PAPER 2) 10842/24 TABLE 4B: STANDARD REDUCTION POTENTIALS TABEL 4B: STANDAARD REDUKSIEPOTENSIALE Half-reactions/Halfreaksies E (V) Li+ + e ⇌ Li  3,05 K+ + e ⇌ K  2,93 Cs+ + e ⇌ Cs  2,92 Increasing oxidising ability/Toenemende oksiderende vermoë Increasing reducing ability/Toenemende reduserende vermoë Ba2+ + 2e ⇌ Ba  2,90 Sr2+ + 2e ⇌ Sr  2,89 Ca2+ + 2e ⇌ Ca  2,87 Na+ + e ⇌ Na  2,71 Mg2+ + 2e ⇌ Mg  2,36 Aℓ3+ + 3e ⇌ Aℓ  1,66 Mn2+ + 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 Sn4+ + 2e ⇌ Sn2+ + 0,15 2+ Cu + 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 Pt2+ + 2 e ⇌ Pt + 1,20 MnO2 + 4H+ + 2e ⇌ Mn2+ + 2H2O + 1,23 O2(g) + 4H+ + 4e ⇌ 2H2O + 1,23 2 Cr2O 7 + 14H+ + 6e ⇌ 3+ 2Cr + 7H2O + 1,33 Cℓ2(g) + 2e ⇌ 2Cℓ + 1,36  MnO 4 + 8H+ + 5e ⇌ 2+ Mn + 4H2O + 1,51 + H2O2 + 2H +2 e  ⇌ 2H2O +1,77 Co3+ + e ⇌ Co2+ + 1,81 F2(g) + 2e ⇌ 2F + 2,87