Physical Sciences Grade 12 P2 Mpumalanga Prelim 2024 Memo

Downloaded from hlayiso.com ————————————————————— DEPARTMENT OF EDUCATION ————————————————————— DEPARTEMENT VAN ONDERWYS ————————————————————— LEFAPHA LA THUTO ————————————————————— ISEBE LEZEMFUNDO ————————————————————— PROVINCIAL PREPARATORY EXAMINATION/ PROVINSIALE VOORBEREIDENDE EKSAMEN GRADE/GRAAD 12 PHYSICAL SCIENCES: CHEMISTRY FISIESE WETENSKAPPE: CHEMIE PAPER/VRAESTEL 2 SEPTEMBER 2024 MARKING GUIDELINES/NASIENRIGLYNE MARKING GUIDELINES/NASIENRIGLYNE MARKS/PUNTE: 150 These marking guidelines consist of 14 pages./ Hierdie nasienriglyne bestaan uit 14 bladsye. Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 2 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne QUESTION 1/VRAAG 1 1.1 A (2) 1.2 D (2) 1.3 C (2) 1.4 B (2) 1.5 B (2) 1.6 A (2) 1.7 B (2) 1.8 A (2) 1.9 C (2) 1.10 A (2) [20] Copy right reserved

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 3 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne QUESTION 2/VRAAG 2 2.1 C✓ (1) 2.2 O ‖ ✓ C O-H (1) 2.3 D✓ (1) 2.4 Formyl (group) ✓/Formiel (groep) (1) 2.5 (Concentrated) sulphuric acid ✓/(Gekonsentreerde) swawelsuur (1) 2.6 E✓ (1) 2.7 C2 H4 O ✓ (1) 2.8 Marking criteria/Nasienkriteria H • Fluoro substituent ✓ Fluorosubstituent H C H • 2 methyl substituents✓ 2 metiel substituente H H H H H • Whole structure correct✓ Hele struktuur korrek H C C C C C C H IF/INDIEN: H-atom/bond omitted/ H F H H H H-atoom/binding uitgelaat. -1 H C H H (3) 2.9 4,4 – dimethyl hexan-2-one/4,4 – dimetielheksan-2-oon 4,4 – dimetiel-2-hexanone/4.4 – dimetiel-2-heksanoon Marking criteria/Nasienkriteria • Correct chain length, ie. hex ✓ Korrekte kettinglengte, bv. heks • Everything else correct: IUPAC name completely correct including numbering, sequence, hyphens and comma. ✓ Alles verder korrek: IUPAC name volledig korrek insluitend nomering, volgorde, koppeltekens en kommas. (2) 2.10 A and/en F✓ (1) [13] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 4 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne QUESTION 3/VRAAG 3 3.1 Marking criteria/Nasienriglyn If any of the underlined key words/phrases in the correct context is omitted deduct 1 mark./Indien enige van die onderstreepte sleutelwoorde/frases in die korrekte konteks uitgelaat is, trek 1 punt af. Compounds with the same molecular formula, but different structural formula.✓✓ Verbindings met dieselfde molekulȇre formule, maar verskillende struktuur formules. (2) 3.2 Chain( isomerism) ✓/Ketting (isomerie) (1) 3.3 Marking Guidelines/Nasienriglyne • Compare the structures/Vergelyk die strukture • Compare strengths of IMF/Vergelyk die sterkte van IMK • Compare energy needed to overcome/break IMF/Vergelyk die energie nodig om kragte te oorkom/breek • Butane (B) (is a straight chain molecule and thus) has a greater surface area ✓ than methyl propane (E) / Betaan(B) is `n reguitketting molekule met n groter kontakoppervlakte as metielpropaan(E). • Butane thus has stronger intermolecular forces ✓ than methyl propane./ Butaan het dus sterker intermolekulëre kragte as metielpropaan. • More energy is needed to overcome the IMF in butane/ Meer energie is dus nodig om die IMK in butaan te oorkom OR • Methyl propane(E) has (a side chain and therefore) a smaller surface area than butane (B) / Metielpropaan(E) het `n syketting en dus `n kleiner kontakoppervlakte as butaan(B). • Methyl propane has weaker intermolecular forces than butane / Metielpropaan het swakker intermolekulëre kragte as butaan. • Less energy is needed to overcome the intermolecular forces in methyl propane/ Minder energie is nodig om die intermolekulëre kragte in metielpropaan te oorkom. (3) 3.4 3.4.1 Homologous series/homoloë reeks ✓ Functional group / funksionele groep (1) 3.4.2 Number of carbons / chain length✓/ surface area / molecular mass Aantal koolstofatome / kettinglengte / kontak oppervlakte / molekulȇre massa (1) 3.4.3 A / ethane✓/etaan It has (the lowest boiling point and thus) the weakest intermolecular force/ London forces✓ therefore the least energy is needed to overcome the forces.✓/ Dit het (die laagste kookpunt en het dus) die swakste intermolekulëre krag/ Londonkragte, wat die minste energie vereis om dit te oorkom. (3) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 5 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne 3.5 Marking criteria/Nasienriglyne • Dependent and independent variable identified Afhanklike en onafhanklike veranderlikes korrek geïdentifiseer • Correct relationship between dependant and independent variables stated Korrekte verwantskap tussen die afhanklike en onafhanklike gestel 1 IF/INDIEN: Directly proportional/Direk eweredig (Max/Maks 2 ) The longer the chain length the higher the boiling point. ✓✓/The greater the surface area the higher the boiling point. Hoe langer die koolstofketting hoe groter die kookpunt./Hoe groter die oppervlakte area hoe groter die kookpunt. Or / of The shorter the chain length / more branched, the lower the boiling point / Less surface area equals a lower boiling point. Hoe korter die koolstofketting, meer vertak hoe laer die kookpunt / Kleiner reaksie oppervlak lei tot laer kookpunt. (2) 3.6 C5H12 + 8O2 ✓→ 5CO2 + 6H2O ✓ (Bal)✓ Marking criteria/Nasienriglyne Reactants✓ Products✓ Balancing✓ (3) [16] QUESTION 4/VRAAG 4 4.1 4.1.1 Cracking ✓/Kraking / Elimination/ Eliminasie (1) 4.1.2 Heptane ✓/Heptaan (2) 4.2 4.2.1 Addition/Hydrogenation✓ Addisie/Hidrogenasie (1) 4.2.2 Butane✓/Butaan (1) 4.2.3 Platinum /Pt ✓ or Palladium /Pd or Nickel /Ni (1) 4.3 Substitution✓/halogenation/chlorination Substitusie/halogenering/chlorinering (1) 4.4 4.4.1 Dehydrohalogenation✓or dehydrochlorination/ Dehidrohalogenering of diehidrochlorinering (1) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 6 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne 4.4.2 Concentrated strong base(NaOH etc), ✓heat ✓/ (2) Gekonsentreerde sterk basis(NaOH, etc), hitte 4.4.3 H Cℓ H H H C C C C H ✓ + NaOH ✓ → H2O + NaCℓ ✓ + H H H H H  H H  H C C C C H H H H Note: Functional group carries a mark regardless the position/ Funksionelegroep kry `n punt ongeag die posisie (5) 4.5 4.5.1 H2O / water✓or dilute sodium hydroxide (NaOH / KOH / LiOH) / verdunde (1) 4.5.2 Secondary ✓/Sekondȇr The C-atom to which the hydroxyl group /OH-group is attached, is attached to two other C-atoms. ✓ Die C-atoom waaraan die hidroksielgroep verbind is, is aan twee ander C-atome verbind. (2) [18] QUESTION 5/VRAAG 5 5.1 NOTE/LET WEL Give the mark for per unit time only if in context of reaction rate. Gee die punt vir per eenheidtyd slegs indien in konteks met reaksietempo. ANY ONE/ENIGE EEN • Change in concentration  of products/reactants per (unit) time.  Verandering in konsentrasie van produkte/reaktanse per (eenheid) tyd. • Change in amount/number of moles/volume/mass of products or reactants per (unit) time. Verandering in hoeveelheid/getal mol/volume/massa van produkte of reaktanse per (eenheid) tyd. • Amount/number of moles/volume/mass of products formed/reactants used per (unit) time. Hoeveelheid/getal mol/volume/massa van produkte gevorm / reaktanse gebruik per eenheids tyd. • Rate of change in concentration/amount/number of moles/volume/mass. Tempo van verandering in konsentrasie/hoeveelheid/getal mol/ volume/massa.  (2 or/of 0) (2) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 7 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne 5.2 Experiment 2✓ (1) 5.3 Larger surface area (state of division). ✓ More effective collisions per unit time/ per second. ✓ Groter reaksie oppervlakte (toestand van verdeeldheid). Meer effektiewe botsings per eenheidstyd en die reaksie tempo verhoog. (2) 5.4 Increase the concentration of HCℓ / verhoog die gekonsetrasie van HCℓ✓ or (1) Catalyst / Katalisator 5.5 Conical flask / Erlenmeyer flask✓ Koniese fles / Erlenmeyerfles (1) 5.6 (Hydrogen) gas is escaping✓/ (Waterstofgas) ontsnap or The flask is open / die fles is oop (1) 5.7 ∆m rate/tempo = Δt 3,5 - 0 ✓ = 4-0 = 0,875 (0,88) (g.s-1)  (2) 5.8 3,5 g ✓ (1) 5.9 m n(H2) =  M 3,5 =  2 = 1,75 mol n(Mg) = n(H2) = 1,75 mol  m(Mg) = nM = (1,75)(24)  = 42 g  (5) 5.10 The hydrochloric acid was in excess /all the magnesium reacted.  Die soutsuur was in oormaat /al die magnesium het gereageer. (1) 5.11 Marking criteria/ Nasienkriteria Graph 3 has a smaller gradient✓ Mass of H2 (g) Graph 2 Grafiek 3 het 'n kleiner gradiënt Graph 3 forms half of the H2 compared to exp 2✓ Grafiek 3 vorm helfte van H2 in vergelyking met  Graph 3  eksp. 2 Time (s) (2) [19] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 8 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne QUESTION 6/VRAAG 6 6.1 The stage in a chemical reaction when the rate of forward reaction equals the rate of reverse reaction.  (2 or 0) Die stadium in 'n chemiese reaksie wanneer die tempo van die voorwaartse reaksie is gelyk aan die tempo van die terugwaarste reaksie.  (2 of 0) OR/OF The stage in a chemical reaction when the concentrations /quantities of reactants and products remain constant. Die stadium in 'n chemiese reaksie wanneer die konsentrasies/hoeveelhede van reaktanse en produkte konstant bly. (2) 6.2 Light brown✓/Ligbruin (1) ACCEPT: colourless/AANVAAR: kleurloos 6.3 Exothermic ✓ • Kc decreases with an increase in temperature✓ • The reverse reaction is favoured✓ Eksotermies • Kc neem af met 'n toename in temperatuur • Die terugwaartse reaksie word bevoordeel (3) 6.4 OPTION 1/OPSIE 1 CALCULATIONS USING MOLES Marking guidelines/Nasienriglyne: (a) n(N2O4) at equilibrium = cV = (3)(0,5) = 1,5 mol (b) Using ratio ✓/Gebruik van verhouding (c) n(NO2) at equilibrium = initial n(NO2) – used n(NO2) ✓ (d) Division of equilibrium moles of NO2 with 0,5 to get equilibrium concentration (e) Correct Kc expression)✓/Korrekte Kc uitdrukking (f) Substitution of Kc as 10 ✓/Substitusie van Kc as 10 (g) Substitution of concentrations into Kc expression (h) Final answer/finale antwoord: 150,6 g  2NO2(g) N2O4(g) Molar ratio 2 1 Molêre verhouding Initial mol X - Aanvanklike mol(mol) 46 Change in mol. 3 1,5 (b) ✓ Verandering in mol(mol) Equilibrium amount (mol) X Ewewig hoeveelheid(mol) - 3 ✓(c) 1,5✓(a) 46 Equilibrium concentration X -3 3 Konsentrasie by ewewig 46 ✓(d) (given) (mol·dm-3) 0,5 Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 9 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne [N2O4 ] KC = ✓ (e) [NO2 ]2 3 10✓ (f) = X ✓ (g) -3 2 [46 ] 0,5 X = 150,6 g ✓ (h) OR 2NO2(g) N2O4(g) Molar ratio 2 1 Molêre verhouding Initial mol n - Aanvanklike mol(mol) Change in mol. 3 1,5 (b) ✓ Verandering in mol(mol) Equilibrium amount (mol) n - 3 ✓(c) 1,5✓(a) Ewewig hoeveelheid(mol) Equilibrium concentration 𝑛-3 ✓(d) 3 Konsentrasie by ewewig 0,5 (given) (mol·dm-3) [N2 O4 ] Kc = (e) ✓ [NO2 ]2 3 10✓ (f) = 𝑛-3 2 ✓ (g) [ 0,5 ] n = 3,274 mol mX = nM = (3,274)(46) = 150,6 g ✓ (h) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 10 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne OPTION 2/OPSIE 2 CALCULATIONS USING CONCENTRATION Marking guidelines/Nasienriglyne: (a) n(N2O4) at equilibrium = change in c (b) Using ratio/Gebruik van verhouding (c) n(NO2) at equilibrium = initial n(NO2) – used n(NO2) (d) Correct Kc expression/Korrekte Kc uitdrukking (e) Substitution of Kc as 10/Substitusie van Kc as 10 (f) Substitution of concentrations into Kc expression (g) The concentration of x(NO2) solving Kc = 6,548 mol∙dm-3 (h) Final answer/finale antwoord: 150,6 g 2NO2(g) N2O4(g) Molar ratio 2 1 Molêre verhouding Initial concentration c - Aanvanklike konsentrasie (mol∙dm-3) Change in concentration. 6 (b) ✓ 3 (a) ✓ Verandering in konsentrasie (mol∙dm-3) Equilibrium concentration c-6 (c)✓ 3 Konsentrasie by ewewig (mol·dm-3) (given) [N2 O4 ] Kc = (d) ✓ [NO2 ]2 3 10✓ (e) = ✓ (f) [x-6]2 [NO2] = 6,548 mol∙dm-3✓ (g) mX = cMV = (6,548)(46)(0,5) = 150,6 g (h) ✓ OPTION 3/OPSIE 3 CALCULATIONS USING CONCENTRATION Marking guidelines/Nasienriglyne: (a) n(N2O4) and n(NO2) at equilibrium = cV ✓ (b) Using ratio ✓/Gebruik van verhouding (c) initial n(NO2) = used n(NO2) + n(NO2) at equilibrium ✓ (d equilibrium concentration of NO2 from Kc calculation (e) Correct Kc expression)✓/Korrekte Kc uitdrukking (f) Substitution of Kc as 10 ✓/Substitusie van Kc as 10 (g) Substitution of concentrations into Kc expression (h) Final answer/finale antwoord: 150,6 g  Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 11 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne 2NO2(g) N2O4(g) Molar ratio 2 1 Molêre verhouding Initial moles 3 + 0,27 0 Aanvanklike konsentrasie (mol) (c ) ✓ Change in mole. 3 (b) ✓ 1,5 Verandering in mol (mol) Equilibrium amount ( mole) 0.27 (a) 1,5(a) ✓ Ewewigs hoeveelheid (mol) Equilibrium concentration 0,548 (d) 3 Konsentrasie by ewewig (mol·dm-3) (given) [N2 O4 ] Kc = (e) ✓ [NO2 ]2 3 10✓ (f) = ✓ (g) [[NO2 ]2 [NO2] = 0,548 mol∙dm-3 ✓ (d) mX = nM = (3,27)(46) = 150,6 g ✓ (h) (8) 6.5 Decrease ✓/Neem af (1) 6.6 6.6.1 Stays the same, ✓ only temperature affects the Kc value ✓/ Bly dieselfde, slegs temperatuur affekteer die Kc waarde (2) 6.6.2 Increase✓ • Higher pressure favours the reaction that forms less moles✓ • The forward reaction is favoured ✓ Verhoog • Hoër druk bevoordeel die reaksie wat minder mol vorm • Die voorwaartse reaksie word bevoordeel (3) [20] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 12 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne QUESTION 7/VRAAG 7 7.1.1 An acid ionises incompletely in water✓ to form a low concentration of H3O+ . ✓ 'n Suur ioniseer onvolledig in water om 'n lae konsentrase H3O+ te vorm. (2) 7.1.2 OPTION 1 OPTION 2 pH = -log[H3O+]✓ [H3O+] = 10-pH ✓ 4,5✓ = -log[H3O+] = 10-4.5 ✓ = 3,16 x 10-5 mol.dm-3 ✓ = 3,16 x 10-5 mol.dm-3 ✓ (3) 7.1.3 Greater than 7 ✓ A strong base (NaOH) reacts with a weak acid (HF) ✓/'n Sterk basis (NaOH) reageer met 'n swak suur (HF) (2) m 7.2.1 n(MgCO3) = M 3,5 =  84 = 0,042 mol n(HCℓ) = 2n(MgCO3) = (2)(0,042) ✓ = 0,084 mol ✓ (3) 7.2.2 POSITIVE MARKING FROM QUESTION 7.2.1 n(NaOH) = cV ✓ = (1,2)(0,02) ✓ = 0,024 mol n(HCℓ)excess = n(NaOH) = 0,024 mol ✓ n(HCℓ)initial = n(reacted) + n(excess) = 0,084 + 0,024 ✓ = 0,108 mol n c(HCℓ) = V 0,108 = ✓ 0,05 = 2,16 mol·dm-3 ✓ Range (2,08 – 2,16) (6) [16] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 13 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne QUESTION 8/VRAAG 8 8.1 8.1.1 Chemical to electrical✓/Chemies na elektries (1) 8.1.2 Concentration/Konsentrasie – 1 mol∙dm-3 ✓ Temperature/Temperatuur - 25°C / 298 K✓ (2) 8.1.3 Fe ✓ Reduction takes place at this electrode ✓/Reduksie vind plaas by hierdie elektrode. OR Fe3+ is a stronger oxidizing agent than Mg2+ / Fe3+ is ‘n sterker oksideermiddel as Mg2+. OR Decrease in oxidation number of Fe3+ / Afname in oksidasiegetal van Fe3+ (2) 8.1.4 Mg → Mg2+ + 2e- ✓✓ (2) 8.1.5 Mg(s) l Mg2+(aq) ✓ll ✓ Fe3+(aq) l Fe(s)✓ NOTE: Ignore phases/NOTA: Ignoreer fases (3) 8.1.6 Salt bridge ✓/Soutbrug (1) 8.2 E θcell = E θcathode − E θanode ✓ = - 0,06 ✓ - (-2,36)✓ = 2,3 V✓ (4) [15] QUESTION 9/VRAAG 9 9.1 ANY ONE/ENIGE EEN: • The chemical process in which electrical energy is converted to chemical energy.  (2 or 0) Die chemiese proses waarin elektriese energie omgeskakel word na chemiese energie. • The use of electrical energy to produce a chemical change. Die gebruik van elektriese energie om 'n chemiese verandering te weeg te bring. • Decomposition of an ionic compound by means of electrical energy. Ontbinding van 'n ioniese verbinding met behulp van elektriese energie. • The process during which and electric current passes through a solution/ionic liquid/molten ionic compound. Die proses waardeur 'n elektriese stroom deur 'n oplossing/ioniese vloeistof/gesmelte ioniese verbinding beweeg. (2) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P1/Grade 12 14 September 2024 Fisiese Wetenskappe/Graad 12 Marking Guidelines/Nasienriglyne 9.2 Red brown deposit/ copper deposit / mass increase / change in colour✓ Rooibruin neerslag/ koper neerslag / toename in massa / kleur verander (1) 9.3 2Cℓ- → Cℓ2 + 2e- ✓✓ (2) 9.4 Chloride ion ✓/Chloorioon (Cℓ-(ag)) (1) 9.5 It conducts electricity through the movement of ions ✓ Dit gelei elektrisiteit deur middel van bewegende ione. (1) 9.6 P✓ Pure copper forms through reduction of Cu2+ at the cathode✓ Suiwer koper vorm deur reduksie van Cu2+ by die katode (2) 9.7 The rate of reduction is equal to the rate of oxidation✓ Die tempo van reduksie is gelyk aan die tempo van oksidasie. (1) 9.8 Ag and Pt is weaker reducing agents ✓than Cu ✓and will not be oxidised✓ OR Cu is a stronger reducing agent than Ag and gets oxidised Ag en Pt is swakker reduseermiddels as Cu en word dus nie geoksideer nie. OF Cu is 'n sterker reduseermiddel as Ag en word dus geoksideer (3) [13] GRAND TOTAL/GROOTTOTAAL: 150 Copy right reserved