Physical Sciences Grade 12 Paper 2 Limpopo Mock 2025 Memo

REPUBLIC OF SOUTH AFRICA DEPARTMENT OF EDUCATION NATIONAL SENIOR CERTIFICATE GRADE 12 PHYSICAL SCIENCES PAPER 2 MEMO PREPARATORY 2025 ee ee ee ee MARKS: 150 TIME: 3 Hours This Marking Guidelines consist of 10 pages including the cover page

QUESTION 1 14 cvy 1.2 AVY 1.3 BYv 1.4 Avy 1.5 Byv 1.6 avy 1.7 Avy 1.8 Byy 1.9 Byy 1.10 Dyv QUESTION 2 24 2.3 2.4 2.5 2.2.1 2.2.2 2.2.3 2.2.4 DoE/Preparatory 2025 Chain isomers are compounds with the same molecular formula but different types of chains. vv Cv 4 — bromo - 2,2 — dimethyipentanev vv, Notes: 1. Bromo, dimethyl identifiedy 2. Pentanev 3. Whole structure correctY Pent — 1 —- enevv Notes: 1. Correct functional groupY 2. Whole structure correctY CnHonY HH \ | id H-—-C—C H Pld Tay H . Correct functional groupy 2. Whole structure correctv CsH12 + 8O2v — 5CO2 + 6H20v (“ balance) Aldehydes Copyright reserved Please turn over (2) (2) (2) (2) (2) (2) (2) (2) (2) (2) [20] (2) (1) (3) (2) (1) (2) (3) (1)

DoE/Preparatory 2025 2.6 20% C — atoms in comp.C = od x Sv =v Compound E has 6 C — atoms 4 “xX = 6¥ and y = 14v OR (x = 6 and y= 14vv) (4) [19] QUESTION 3 3.1 Melting point is the temperature at which the solid and the liquid phases of a substance are at equilibrium. vv (2) 3.2 As the chain length/molar mass/number of carbon atoms increases, the boiling/melting point increases. v ¥ (2) 3.3 Stronger than. ” (1) 3.4 Fair. Y The compounds belong to the same homologous/intermolecular force/functional group/there is only one independent variable. v (2) 3.5 Gas. v (1) 3.6 e Propane has a longer chain length/larger/ surface area/ bigger molecular size/more carbon atoms than ethane.v e Both have London forces/dispersion/dipole-dipole which are stronger between propane molecules than in ethane./the intermolecular forces of propane are stronger e More energy is needed to overcome the intermolecular force in propane than in ethane.v OR e Ethane has shorter chain length/smaller surface area/smaller molecular size/less carbon atoms than propane.“ e Both have London forces/dispersion/dipole-dipole which are weaker between ethane molecules than in propane.” e Less energy in needed to overcome the intermolecular forces in ethane than in propane.v (3) [11] Copyright reserved Please turn over

QUESTION 4 4.44 4.1.2 4.21 4.2.2 4.3.1 4.3.2 4.4.1 4.4.2 4.5.1 4.5.2 DoE/Preparatory 2025 Substitution/hydrolysis~ Butan — 2 - ol’ “ Accept 2-butanol (1 mark for butanol, 1 mark for position) Ai H \\ i v Ct+-CTH Notes: YW) \ Vv ce ri 1. Correct functional groupY We 2. Whole structure correctv H (Strong) Heatv’ H v| | rH H clH H v Lf tm “ iH Vv H—C—C—C—C—H org ro] tod eee H~ \ ws v H HH H conc. KOH in ethanol H + 4H H + K—Cl Positive marking form 4.3.1 But-2-ene.v v fAccept 2-Butene (1 mark for butene, 1 mark for position) Addition/hydrogenation. ~ Ni/Pt/Pd/Nickel/Platinum/Palladium.” Cracking is the chemical process in which longer chain hydrocarbon molecules are broken down to shorter more useful molecules. v ¥ Catalyst (Pt, Pd and Ni).” Copyright reserved Please turn over (1) (2) (2) (1) (5) (2) (1) (1) (2) (1) [18]

DoE/Preparatory 2025 QUESTION 5 5.4 Rate of reaction is the change in concentration of reactants or products per unit time.v Vv (2) 5.2 Neutralisation reaction.v /Acid-base reaction (1) 5.3 State of division/surface area.” (1) 5.4 Rate of reaction.” (1) 5.5 n(COz) = wy =e tt 22400 = 0,002366 mol n(HCl) _ 2(0,002366) / “22.400 = 0,004732 mol Rate = “v At = 0,004732 /, 60 . - : (5) = 0,0000789 mol.s™!/(7,89 x 1075mol. s~1)v [10] Copyright reserved Please turn over

QUESTION 6 6.1.1 6.1.2 6.2.1 6.2.2 6.2.3 DoE/Preparatory 2025 Chemical equilibrium is a dynamic equilibrium when the rate of the forward reaction equals to the rate of the reverse reaction.v Vv | SO2 O22 | SO | Ratio 2 1 2 Initial amount(mol) x 0.5 0 Change -0,75 -0,375Y 0,75 Equilibrium x-—0,75 0,125” 0,75 Concentration =—= 0,0625 | 0,375 S03] K.= [ | [SO2]?[02] 10V = (0,375) v (£278)" 0625 fi x= 1,70 molv Positive marking from 6.1.2 m =—Vv n M m = —VvY 1,70 r3 m= 108, 8gv Decreases.v Stays the same.v (2) ¥ Ratio (8) (3) (1) (1) Decreases.” A decrease in pressure favours the reaction that produces more moles of gas/more volume.v The reverse reaction is favoured.” Copyright reserved (3) [18] Please turn over

DoE/Preparatory 2025 QUESTION 7 7.4 A weak base is a base that ionises/dissociates incompletely in water to form a low concentration of hydroxide ions.v¥ (2) 7.2 Option 1: [ H30*] = 2 x 0,02= 0,04 mol.dm? Kw = [ Hs0*][OH]¥ 1x 10-4 = 0,04 [OH ]v [OH] = 2,5 x 10°73 mol.dm3v Option 2: pH = -log[Hs0*]v = -log{0,04) v = 1,398 pH + pOH = 14 1,398 + pOH = 14v pOH = 12,602 pOH = -log[OH] 12,602 = -logjOH] [OH7] = 2,50 x 10°3mol.dm3v Copyright reserved Please turn over

7.3.1 7.3.2 7.4.1 7.4.2 7.4.3 DoE/Preparatory 2025 n(H2SO4) = cvv = (0,02)(0,025)v = 06,0005 mal n(VH3) = 2(0,0005)” = 0,001 mol [NH] in diluted solution = ; _ 0,001 0,0312v = m0,032051 mol n(NHs) in 250 cm$ = cv = 0,032051 x 0,25v = 0,0080128 mol n(NHs) in 250 cm? = 7(NH3) in 20 cm3 of undiluted solution NH;] == [NH] = 5 = 0,080128 /, 0,02 = 0,4 mol.dm=3v Below 7v NHa4* + HoOvw ———-» NHs3 + Hs0*tvv An Ampholyte is a substance that can act as either an acid or a basevv HC204-v H2C204v and H3O*v Copyright reserved Please turn over (7) (4) (1) (2) [22]

DoE/Preparatory 2025 QUESTION 8 8.1 A galvanic cell is a cell in which chemical energy is converted to electrical energy.vv (2) 8.2 Concentration of 1mol.dm3v Temperature of 25°C/298Kv (2) 8.3.1 Pty (1) 8.3.2 Crv (1) 8.4 2 mol.dm3v (2) 8.5 3Sn4* + 2Crv ——> 3Sn2 + 2Cr3+v (vbalancing) (3) 8.6 E® cet = E® cathode - E®anode” = +0,15v- (-0,74)v = +0,89Vv (4) 8.7 Decreases.v (1) [16] Copyright reserved Please turn over

DoE/Preparatory 2025 QUESTION 9 9.4 Electrolysis is the chemical process in which electrical energy is converted to chemical energy.v v (2) 9.2 Cu———* Cut + 2e vv Notes/Notas: Ignore phases/ignoreer fases Cu?* + 2e° — Cu (2/2) Cu** + 2e° @ Cu (0/2) Cu © Cu?* + 2e (1/2) Cu?* + 2e° > Cu (0/2) (2) 9.3 Impure copper.v (1) 9.4.1 Zinc/Nickel/Zn/Ni.v (1) 9.4.2 Zinc/Nickel is a stronger reducing agentv than copper.” (2) 9.4.3 They will fall to the bottom.” (1) 9.5 mass of copper + impurutues = 600 — 390V = 210g mass of pure copper = 320 — 150V = 170g % purity = = x 100V = 80,95%Y (4) 9.6 It remains constant.v The rate of oxidation of copper is equal to the rate of reduction of copper ions.v v (3) [16] TOTAL: 150 Copyright reserved