Gr 12 Physical Sciences P2 (English and Afrikaans) June 2024 Possible Answers_hlayiso.com_.pdf

Downloaded from hlayiso.com JUNE EXAMINATION JUNIE EKSAMEN GRADE/GRAAD 12 2024 MARKING GUIDELINES/ NASIENRIGLYNE PHYSICAL SCIENCES: CHEMISTRY/ FISIESE WETENSKAPPE: CHEMIE (PAPER/VRAESTEL 2) 13 pages/bladsye

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 QUESTION/VRAAG 1 1.1 A ✓✓ (2) 1.2 C ✓✓ (2) 1.3 B ✓✓ (2) 1.4 D ✓✓ (2) 1.5 A ✓✓ (2) 1.6 D ✓✓ (2) 1.7 C ✓✓ (2) 1.8 B or C or D ✓✓ (2) 1.9 D ✓✓ (2) 1.10 A ✓✓ (2) [20] QUESTION/VRAAG 2 2.1 A series of organic compounds that can be described by the same general formula. OR A series of organic compounds in which one member differs from the next with a CH2 group. ✓✓ (2 or 0) ʼn Reeks organiese verbindings wat deur dieselfde algemene formule beskryf kan word. OF ʼn Reeks organiese verbindings waarin die een lid van die volgende verskil met ʼn CH2-groep. (2) 2.2 2.2.1 Aldehydes/Aldehiede ✓ (1) 2.2.2 CH3CH2CH2CHO ✓ OR/OF CHOCH2CH2CH3 OR/OF CHO(CH2)2CH3 (do not accept OH) (moet nie OH aanvaar nie) (1) 2.2.3 Butan-2-one/Butan-2-oon ✓✓ Accept: 2-butanone / butanone Aanvaar 2-butanoon / butanoon (2) Marking criteria/Nasienriglyne • Correct functional group: -ONE/Korrekte funksionele groep: EEN ✓ • IUPAC name correct ✓ 2

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 2.3 2.3.1 3,4-dibromo-2,2-dimethylpentane ✓✓✓ 3,4-dibromo-2,2-dimetielpentaan (3) Marking criteria/Nasienriglyne • Correct stem (pentane)/korrekte stamnaam (pentaan) ✓ • All substituents (bromo and methyl) were correctly identified./Alle substituente (broom en metiel) is korrek geïdentifiseer. ✓ • IUPAC name is completely correct including numbering, sequence, hyphens and commas./IUPAC-naam is heeltemal korrek insluitend nommering, volgorde, koppeltekens en kommas ✓ 2.3.2 CnH2n+1COOH OR/OF CnH2nO2 ✓ (1) 2.4 2.4.1 C & D ✓✓ (must have both)/(moet beide hê) (2 or 0) (2) 2.4.2 F✓ (1) 2.5 2.5.1 (2) Marking criteria/Nasienriglyne • Correct stem (butane)/korrekte stam (butaan) ✓/ • Functional group OH and methyl on the second carbon/Funksionele groep OH en metiel op die tweede koolstof✓ 2.5.2 Tertiary/Tersiêr ✓ (1) 2.5.3 Three carbon atoms ✓ are bonded to the carbon atom to which the hydroxyl (OH)/functional group is bonded. ✓ Drie koolstofatome is verbind aan die koolstofatoom waaraan die hidroksielgroep (OH)/ funksionele groep verbind is. (2) 3

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 2.6 𝑚 % m = 100 g M n=𝑀 Ratio/Verhouding Carbon/ 81,82 12 81,82 6,82 =1 ×3 3 6,82 Koolstof 12 H 18,18 1 18,18 18,81 =2,67 ×3 ✓ 8 ✓ 6,82 1 ✓ C3H8 ✓ (4) Marking criteria/Nasienriglyne 𝑚 • Substitute 12 and 1 respectively into n = 𝑀 /Vervang 12 en 1 onderskeidelik in 𝑚 n=𝑀 ✓ • Divide by the smallest amount of mols 6,82 ✓/Deel deur die kleinste aantal mol 6,82 • Multiply by 3 to get the smallest whole number ratio/Vermenigvuldig met 3 om die kleinste heelgetal verhouding te kry ✓ • Correct empirical formula C3H8/Korrekte empiriese formule C3H8 ✓ [22] QUESTION/VRAAG 3 3.1 Boiling point – The temperature at which the vapour pressure of a substance equals atmospheric pressure. ✓✓ Kookpunt – Die temperatuur waarby die dampdruk van die stof gelyk is aan atmosferiese druk. (2) Marking criteria/Nasienkriteria If any of the underlined key words/phrases in the correct context is omitted deduct 1 mark./Indien enige van die onderstreepte sleutel woorde/frases in die korrekte konteks uitgelaat is, trek 1 punt af. 3.2 3.2.1 Chain length/molar mass/surface area ✓ (do not accept IUPAC name) Kettinglengte/molêre massa/kontakoppervlakte (moet nie IUPAC-naam aanvaar nie) (1) 3.2.2 Boiling point/kookpunt ✓ (1) 3.2.3 Homologous series ✓ type of intermolecular force (do not accept same volume, same kind of apparatus) Homoloë reeks / tipe intermolekulȇre kragte (moet nie aanvaar dieselfde volume, dieselfde soort apparaat nie) (1) 4

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 3.3 What is the relationship between chain length/molar mass/surface area and boiling point? ✓✓ Wat is die verwantskap tussen die kettinglengte/molêre massa/kontakoppervlakte en kookpunt? (2) Marking criteria/Nasienriglyne • Must mention INDEPENDENT and DEPENDENT variables ✓ Moet die ONAFHANKLIKE en AFHANKLIKE veranderlikes noem • Answer to the question CANNOT be YES OR NO ✓ Antwoord op die vraag mag nie JA of NEE wees nie. 3.4 (ONE reasonable answer) Keep away from an open flame, OR work in a fume cupboard, OR heat in a water bath. ✓ (EEN redelike antwoord) Hou weg van ʼn oop vlam, OF werk in ʼn dampkas, OF verhit in ʼn waterbad. (1) 3.5 C ✓, it has the highest boiling point. ✓ C, dit het die hoogste kookpunt. (2) 3.6 Higher than/Hoër as ✓ (1) 3.7 • INTERMOLECULAR FORCES and STRENGTH As the chain length increases, ✓ the strength of the London/ intermolecular forces increases, ✓ • ENERGY Therefore more energy is needed to overcome the intermolecular forces leading to a higher boiling point. ✓ • INTERMOLEKULÊRE KRAGTE en STERKTE As die kettinglengte verhoog, verhoog die sterkte van die London/ intermolekulêre kragte. • ENERGIE Daarom word meer energie benodig om die intermolekulêre kragte te oorkom wat dan tot ʼn hoër kookpunt lei. (3) Marking criteria/Nasienriglyne: • Identify the type of intermolecular force./Identifiseer die tipe intermolekulêre kragte. ✓ • Refer to the strength of intermolecular forces./Verwys na die sterkte van die intermolekulêre kragte. ✓ • Mention the energy required to overcome intermolecular forces./Noem die energie benodig om die intermolekulêre kragte te oorkom. ✓ NO MARK if a learner says more energy required to BREAK BONDS/ GEEN PUNTE indien ʼn leerder skryf meer energie benodig om BINDINGS TE BREEK NIE. 5

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 3.8 3.8.1 J✓ (1) 3.8.2 The sunlight supplies sufficient energy (heat) to meet the activation energy of the reaction. ✓Will react with the UV of the sunlight. Die sonlig verskaf genoeg energie (hitte) om gelyk te wees aan die aktiveringsenergie van die reaksie. Sal reageer met die UV van die son. (1) 3.8.3 C4H8Br2 ✓✓ (if only one Br is shown ½) (indien slegs een Br gewys word ½) (2) 3.8.4 2C4H10 ✓ + 13O2 → 8CO2 + 10H2O ✓ bal ✓ Ignore phases and double arrows in answers / Ignoreer fases en dubbel pyl in antwoord (3) [21] QUESTION/VRAAG 4 4.1 Compounds in which there are no multiple bonds between carbon atoms in their hydrocarbon chain. ✓✓ (2 OR 0) OR A compound in which there are only single bonds between the carbon atoms in the chain. Verbindings waarin daar geen meervoudige bindings tussen C-atome in hul koolwaterstofkettings is nie. (2 OF 0) OF ‘n Verbinding waarin daar slegs enkel bindings is tussen die koolstofatome in ‘n ketting. (2) 4.2 4.2.1 Substitution/Substitusie ✓ (1) 4.2.2 Potassium bromide/KBr ✓ Kaliumbromied/KBr (1) 4.2.3 Dilute strong base OR mild heat ✓ OR KOH(aq) Verdunde sterk basis OF matige hitte OF KOH(aq) (1) 4.3 4.3.1 Pentan-2-ol ✓✓ Pentan-2-ol Accept 2-pentanol / Aanvaar 2-pentanol (2) Marking criteria/Nasienriglyne • Correct stem (pentan)/Korrekte stam (pentan) ✓ • IUPAC name is completely correct including numbering, sequence, hyphens and commas./ IUPAC naam is heeltemal korrek met alle nommering, volgorde, koppeltekens en kommas. ✓ 4.3.2 Elimination OR Dehydration/Eliminasie OF Dehidrasie ✓ (1) 6

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 4.3.3 H H H H ✓ ✓ H C C C C C H H H H H (2) Marking criteria/Nasienriglyne • 5 carbons in the chain/5 koolstowwe in die ketting ✓ • Functional group C = C/Funksionele groep C = C ✓ 4.3.4 H2O ✓ (1) 4.4 4.4.1 Hydrogenation/Hidrogenasie of hidrogenering ✓ (1) 4.4.2 Pt OR/OF Pd OR/OF Ni ✓ (1) ✓ 4.5 4.5.1 H H H O H H C C C O C C H ✓ ✓ H H H H (3) Marking criteria/Nasienriglyne: • Functional group/funksionele groep ✓ • correct number of carbon on either side of the functional group/korrekte hoeveelheid koolstowwe aan beide kante van die funksionele groep ✓ • Whole structure is correct/Hele struktuur is korrek ✓ 4.5.2 Propyl ✓ethanoate ✓ Propieletanoaat (2) Sulphuric acid/ hydrogensulphate ✓ 4.5.3 Swawelsuur / waterstofsulfaat (1) 7

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 4.5.4 METHOD 1: C3H8OH + CH3COOH → C5H10O2 + H2O M(C5H10O2) = 102 g.mol-1 M(C3H8OH) = 61 g.mol-1 𝑚 m = 90,78 g n=𝑀 𝑚 n=𝑀 𝑚 0,89 = ✓ 90,78 61 = 102 ✓ m = 54,29 g = 0,89 mol Percentage purity/ n(C5H10O2) : n(C3H8OH) Persentasie suiwerheid = 𝑃𝑢𝑟𝑒 𝑚𝑎𝑠𝑠/𝑆𝑢𝑖𝑤𝑒𝑟 𝑚𝑎𝑠𝑠𝑎 1:1 × 100 𝐼𝑚𝑝𝑢𝑟𝑒 𝑚𝑎𝑠𝑠/𝑂𝑛𝑠𝑢𝑖𝑤𝑒𝑟 𝑚𝑎𝑠𝑠𝑎 0,89 : 0,89✓ 54,29 = ✓ ×100 60 = 90,48% ✓ METHOD 2: C3H7OH + CH3COOH → C5H10O2 + H2O M(C5H10O2) = 102 g.mol-1 M(C3H7OH) = 60 g.mol-1 𝑚 m = 90,78 g n=𝑀 𝑚 n=𝑀 𝑚 0,89 = ✓ 90,78 60 = 102 ✓ m = 53,4 g = 0,89 mol Percentage purity/ n(C5H10O2) : n(C3H8OH) Persentasie suiwerheid = 𝑃𝑢𝑟𝑒 𝑚𝑎𝑠𝑠/𝑆𝑢𝑖𝑤𝑒𝑟 𝑚𝑎𝑠𝑠𝑎 1:1 × 100 𝐼𝑚𝑝𝑢𝑟𝑒 𝑚𝑎𝑠𝑠/𝑂𝑛𝑠𝑢𝑖𝑤𝑒𝑟 𝑚𝑎𝑠𝑠𝑎 0,89 : 0,89✓ 53,4 = 60 ✓ ×100 = 89% ✓ (5) Marking criteria/nasienriglyne 𝑚 • Substitute 102 g·mol-1 into n= 𝑀 ✓ 𝑚 Inveranging van 102 g·mol-1 in n= 𝑀 • Use the mol ratio: n(C5H10O2) : n(C3H8OH) = 1 : 1 ✓ Gebruik die mol verhouding: n(C5H10O2) : n(C3H8OH) = 1 : 1 𝑚 • Substitute 61 g·mol-1 into n= 𝑀 ✓ 𝑚 Invervanging van 61 g·mol-1 in n= 𝑀 • Substitute 60 g as the impure mass ✓ Invervanging van 60 g as die onsuiwer massa • Final answer: 89 - 90,5% ✓ Finale antwoord: 89 - 90,5% [24] 8

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 QUESTION/VRAAG 5 5.1 Change in concentration of reactants or products per unit time ✓✓ (2 or 0) Verandering in konsentrasie van reaktante of produkte per eenheid tyd. (2 of 0) (2) 5.2 As the concentration of the acid decreases, the rate of reaction will also decrease. ✓✓ OR As the concentration of the acid increases, the rate of the reaction will increase. Soos die konsentrasie van die suur afneem, sal die tempo van die reaksie ook afneem. OF Soos die konsentrasie van die suur toeneem sal die tempo van die reaksie ook toeneem. (2) Marking criteria/Nasienriglyne: • Identify variables correct ✓ Identifiseer die veranderlikes korrek • Correct relationship ✓ Korrekte verwantskappe 5.3 OPTION 1/OPSIE 1: n n c=V c=V n 0,03 2 = 0,015 ✓ c = 0,065 ✓ n = 0,03 mol c = 0,46 mol. dm−3 ✓ OPTION 2/OPSIE 2: c1V1 = c2V2 (2)(0,015) ✓= c2 (0,065) ✓ c2 = 0,46 mol·dm-3 ✓ (3) 5.4 Learners should keep the state of division/surface area of the Mg-ribbon the same ✓ and the initial temperature. ✓ Leerders moet die toestand van verdeeldheid/die oppervlakarea van die Mg lint konstant hou en die aanvanklike temperatuur. (2) 9

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 5.5 The Mg is the limiting reagent and determines the amount of product. ✓ OR The same mass of magnesium was used in each experiment. DO NOT ACCEPT: HCℓ is in excess Die Mg is die beperkende reagens en bepaal die hoeveelheid produkte wat vorm. OF Dieselfde massa magnesium is in elke eksperiment gebruik. MOET NIE AANVAAR: HCℓ is in oormaat nie. (1) 5.6 5.6.1 60 (cm3) ✓ (1) 5.6.2 42 (cm3) ✓ (1) 5.7 Experiment 1 ✓ In the same time, more product ✓is produced and the gradient of the graph is steeper. ✓ Eksperiment 1 In dieselfde tyd word meer produkte geproduseer en die gradiënt van die grafiek is steiler. (3) 5.8 Marking criteria/Nasienriglyne 𝑉 • Use volume of 60 cm3/ 0,06 dm3 in n = 𝑉 𝑚 𝑉 Gebruik volume van 60 cm3 in 𝑛 = 𝑉𝑚 • Ratio 1:1/Verhouding 1:1 • Use M = 24/Gebruik M = 24 • Substitute in rate equation Vervang in tempo vergelyking • Answer 0,001/Antwoord 0,001 𝑉 n=𝑉 nMg = nH2 ✓ mMg = nxM 𝑚 0,06 n = 24 ✓ = 0,0025 mol = 0,0025 x 24✓ n = 0,0025 mol = 0,06 g ∆𝑚 Rate/Tempo = - ∆𝑡 0−0,06 = − 60 ✓ = 0,001(g.s-1) ✓ Answer must be positive/Antwoord moet positief wees (5) [20] 10

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 QUESTION/VRAAG 6: 6.1 Endothermic ✓ ∆H is greater that zero/is positive ✓ Endotermies ΔH is groter as nul/is positief (2) 6.2 6.2.1 Reverse✓ The amount of product decreases with time. ✓ Terugwaarts Die hoeveelheid produkte verminder met tyd. (2) 6.2.2 Equal to/Gelyk aan ✓ (1) 𝑚 𝑚 6.2.3 n(H2O)= 𝑀 n(C2) = 𝑀 5 5 =18 = 71 = 0,28mol = 0,07mol H2O C2 HC O2 Ratio 2 2 4 1 Verhouding Initial mole 0,28✓ 0,07✓ 1 0,3✓ Aanvanklike mol Ratio ✓ Change +0,4 +0,4 -0,8 -0,2 Verandering Equilibrium 0,68 0,47 0,2 0,1✓ Ewewig n 0,68 0,47 0,2 0,1 c= ✓ 5 V 5 5 5 =0,02 =0,136 =0,094 =0,04 [HC]4 [O ] K c = [H O]2[C2]2 ✓ 2 2 (0,04)4 (0,02) = (0,136)2 (0,094)2 ✓ = 0,0003 ✓ (3,15 x 10-4) (9) Marking criteria • Calculate the mole of water. ✓ • Calculate the mole of Cℓ2 ✓ • Substitution of initial mole for both HCℓ and O2 ✓ • Correct use of ratio ✓ • Correct mol at equilibrium for O2. ✓ • Divide by volume of 5 ✓ • Kc expression ✓ (Wrong Kc max 7/9) • Substitution of values from Equilibrium concentration ✓ • Correct answer. ✓ 11

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 Nasienkriteria: • Bereken die mol water. ✓ • Bereken die mol Cℓ2 ✓ • Vervang beide HCℓ en O2 ✓ • Korrekte gebruik van verhouding ✓ • Korrekte mol by ewewig O2. ✓ • Deel deur volume van 5 ✓ • Kc uitdrukking ✓ (Verkeerde Kc maks 7/9) • Vervanging van waardes van ewewigskonstante ✓ • Korrekte antwoord ✓ 6.3 Remains the same ✓ Only temperature affects Kc. ✓ Bly dieselfde Slegs temperatuur affekteer Kc. (2) 6.4 Marking criteria/Nasienkriteria: B • Both axes correctly labelled./Asse A korrek benoem ✓ • Shape of Ep curve for endothermic reaction as shown./Vorm van kurwe vir endotermiese reaksie soos getoon. (B) ✓✓ • Added catalyst/Bygevoegde katalisator ✓ (A) (4) [20] QUESTION 7/VRAAG 7: 7.1 7.1.1 An acid is a substance that produces hydrogen ions (H+) / hydronium ions (H3O+) when in solution. ✓✓ ʼn Suur is ʼn stof wat waterstof ione produseer (H+) hidroniuim ione (H3O+) wanneer dit in oplossing is. (2) 7.1.2 It ionises to form 2 protons/Dit ioniseer om 2 protone te vorm. ✓ (1) 7.2 7.2.1 Ampholyte or amphiprotic /amfoliet of amfiproties ✓ (1) 12

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES FISIESE WETENSKAPPE: CHEMIE NASIENRIGLYNE (PAPER/VRAESTEL 2) GR12 0623 7.2.2 HCO3- (aq) + H2O(ℓ) ⇌ H2CO3(aq) + OH-(aq) b1 a2 a1 b2 ✓ ✓ (2) 7.3 7.3.1 OPTION 1/OPSIE 1: OPTION 2/OPSIE 2: m 𝒏 ✓ 𝒎 c= ✓ 𝒄=𝑽 𝒏=𝑴 MV 𝑚 𝒎 0,25 = (36,5)(2,5) ✓✓ 𝒏 = (𝟎, 𝟐𝟓)(𝟐, 𝟓) ✓ 𝟎, 𝟔𝟐𝟓 = 𝟑𝟔,𝟓 ✓ n = 0,625 m = 22,82 g ✓ m = 22,82 g ✓ range/gebied: 22,82 – 23 range/gebied: 22,82 – 23 (4) 7.3.2 OPTION 1/OPSIE 1: OPTION 2/OPSIE 2: 𝒏 𝒄𝒂 = ca Va n 𝑽 = a n = (0,25)(0,05) ✓ cb Vb nb n = 0,0125 mol (0,25)(50)✓ 2 = ✓ nb = ½na✓ cb (20)✓ 1 = 0,00625 mol cb = 0,31 mol·dm-3✓ 𝒏 𝒄𝒃 = 𝑽 0,00625 cb = ✓ 0,02 cb = 0,31 mol·dm-3✓ (4) 7.3.3 Methyl orange. ✓ Strong acid reacts with weak base ✓ Metieloranje Sterk suur reageer met ʼn swak basis. (2) [16] QUESTION/VRAAG 8: 8.1 8.1.1 Oxidation is the loss of electrons Oksidasie is die verlies van elektrone. ✓✓ (2) 8.1.2 Oxidation/Oksidasie ✓ Cu0 ✓→ Cu2+✓ (3) 8.2 METHOD 1: MnO42- METHOD 2: MnO4- x + (4(-2)) = -2 x + (4(-2)) = -1 x = +6 ✓✓ x = +7 (2) [7] TOTAL/TOTAAL: 150 13