Physical Sciences Grade 10 P2 Gauteng November 2023 Memo

Downloaded from hlayiso.com PROVINCIAL EXAMINATION NOVEMBER 2023 GRADE 10 MARKING GUIDELINES PHYSICAL SCIENCES: CHEMISTRY (PAPER 2) 6 pages

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES (PAPER 2) GRADE 10 QUESTION 1 MULTIPLE-CHOICE QUESTIONS 1.1 D ✓✓ (2) 1.2 C ✓✓ (2) 1.3 D ✓✓ (2) 1.4 C ✓✓ (2) 1.5 A ✓✓ (2) 1.6 B ✓✓ (2) 1.7 A ✓✓ (2) 1.8 B ✓✓ (2) 1.9 C ✓✓ (2) [18] QUESTION 2 2.1 2.1.1 OH– ✓ (1) 2.1.2 Si ✓ (1) 2.1.3 Ni ✓ (1) 2.1.4 C✓ (1) 2.1.5 Brass ✓ (1) 2.1.6 Br2 ✓ (1) 2.2 C has greater ionisation energy than Si. ✓ (1) 2

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES (PAPER 2) GRADE 10 2.3 3P4 3S2 2P6 2S2 1S2 ✓ energy level 1 ✓ energy level 2 ✓ energy level 3 (3) 2.4 2.4.1 Free of water. ✓✓ (2) 2.4.2 CuSO4∙x H2O → CuSO4 + xH2O 10g 6,4g ∆m = 10 – 6,4 = 3,6 g ✓ 6,4 n (CuSO4) = m/M = ✓ = 0,04 mol 159,5 n(CuSO4) : n(H2O) 3,6 0,04 : 0,2 18 ✓ = 0,2 mol n (H2O) = 1:5 ∴x=5✓ (4) [16] QUESTION 3 3.1 The temperature at which a solid, given sufficient heat, becomes a liquid. ✓✓ (2) 3.2 1,013 x 105 Pa or 101,3 kPa or 1 atm or 1 bar or pressure at sea level ✓ (1) 3.3 Thermometer ✓ (1) 3.4 Liquid ✓ (1) 3.5 – Temperature remains constant, phase change is taking place (liquid to gas). ✓ – All the heat absorbed is used to weaken the intermolecular forces. ✓ – Kinetic energy remains constant, but potential energy increases. ✓ (3) 3.6 – Ethanol will boil faster than water. ✓ – Ethanol boils at 78 °C and water boils at a higher temperature, 100 °C at standard pressure. ✓ – The water molecules need more energy to overcome the stronger forces. ✓ (3) [11] 3

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES (PAPER 2) GRADE 10 , QUESTION 4 4.1 Atoms of the same element, with the same number of protons but different number of neutrons. ✓✓ (2) 4.2 Sr ✓ (1) 4.3 2✓ (1) 4.4 – Atomic radius decreases across the period and increases down the group. ✓ – Strontium's atomic radius is bigger than that of Magnesium. ✓ (2) (84×0,56) + (86×9,86) + (87×7) + (88×82,58)✓ 4.5 Average atomic mass = 100 ✓ = 87,71 ≈ 88 ✓ (3) [9] QUESTION 5 5.1 The simplest whole-number ratio of atoms in a compound. ✓✓ (2) 5.2 5.2.1 0,73 g ✓ (1) 5.2.2 m n= ✓ M 1,09 n = ✓ = 0,09 mol C 12 0,18 n= ✓ = 0,18 mol H 1 0,73 n = ✓ = 0,046 mol O 16 0,09 0,18 0,046 : : ✓ 0,046 0,046 0,046 2:4:1 Empirese formule = C2H4O ✓ (6) 5.3 Empirical formula molar Mass = 44 g.mol-1 ✓ 88 ratio = =2✓ 44 Molecular formula = C4H8O2 ✓ (3) [12] 4

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES (PAPER 2) GRADE 10 QUESTION 6 6.1 Na2CO3 + 2HCl → 2NaCl + CO2 + H2O ✓✓ (2) 6.2 Carbon (IV) oxide or carbon dioxide ✓ and CO2 ✓ (2) 6.3 6.3.1 CO2 ; H2O of HCl ✓✓ (Any TWO) (2) 6.3.2 NaCl ✓ and Na2CO3 ✓ (2) 6.4 6.4.1 ✓✓ (2) 6.4.2 ✓✓ (2) 6.5 M(Na2CO3) = (2 x 23) + 12 + (3 x 16) = 106 g.mol-1 ✓✓ (2) 6.6 m n = ✓ M 3 𝑛 = ✓ 106 n = 0,028 mol ✓ (3) 6.7 N n =N ✓ A N 0,028 = 6,02 x 1023 ✓ N = 1,7 x 1022 formula units ✓ n(Na2CO3 ) : n (O) 1:3 1,7 x 1022 : 5,11 x 1022 oxygen atoms ✓ (4) [21] 5

Downloaded from hlayiso.com PHYSICAL SCIENCES: CHEMISTRY MARKING GUIDELINES (PAPER 2) GRADE 10 QUESTION 7 7.1 The amount of substance containing the same number of elementary particles (atoms, ions or molecules) as there are atoms in 12 g of carbon-12.✓✓ (2) 7.2 45 cm3 or 0,045 dm3 ✓✓ (2) 7.3 Bubbles/Effervescence of hydrogen gas in the conical flask. ✓ (1) 7.4 V n= ✓ Vm 0,045 ✓ = 22,4 ✓ = 0,002 mol or 2,0 x 10-3 mol ✓ (4) 7.5 n(Mg) : n(H2) 1:1 0,002 : 0,002 ✓ m n= ✓ M 𝑚 0,002 = =✓ 24 m = 0,048 g or 0,05 g ✓ (4) [13] TOTAL: 100 6