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CIE Jun 2015 v2 Paper 2 Q1
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![Answer all the questions in the spaces provided. (a) Chemists recognise that atoms are made of three types of particle. Complete the following table with their names and properties. name of particle relative mass relative charge +1 1/1836 (b) Most elements exist naturally as a mixture of isotopes, each with their own relative isotopic mass. The mass spectrum of an element reveals the abundances of these isotopes, which can be used to calculate the relative atomic mass of the element. Magnesium has three stable isotopes. Information about two of these isotopes is given. [3] isotope 24Mg 26Mg relative isotopic mass percentage abundance 24.0 26.0 79.0 11.0 (i) De ne the term relative isotopic mass.[2] (ii) The relative atomic mass of magnesium is 24.3. Calculate the percentage abundance and hence the relative isotopic mass of the third isotope of magnesium. Give your answer to three signi cantgures percentage abundance =UCLES 2015 9701/22/M/J/15 isotopic mass =[3]<br />
(c) Magnesium can be produced by electrolysis of magnesium chloride in a molten mixture of salts. (i) Give equations for the anode and cathode reactions during the electrolysis of molten magnesium chloride, MgCl 2. anodecathode[2] The electrolysis is carried out under an atmosphere of hydrogen chloride gas to convert any magnesium oxide impurity into magnesium chloride. (ii) An investigation of the reaction between magnesium oxide and hydrogen chloride gas showed that an intermediate product was formed with the composition by mass Mg, 31.65%; O, 20.84%; H, 1.31% and Cl, 46.20%. Calculate the empirical formula of this intermediate compound. empirical formula[2] (d) The acid/base behaviour of the oxides in the third period varies across the period. (i) Describe this behaviour and explain it with reference to the structure and bonding of sodium oxide, Na2O, aluminium oxide, Al 2O3, and sulfur trioxide, SO3.[2] (ii) Write equations for reactions of these three oxides with hydrochloric acid and/or sodium hydroxide as appropriate.[4]UCLES 2015 9701/22/M/J/15 [Total: 18] [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/June_2015_v2_QP_-_Paper_2_CIE_Chemistry_A-level_1-0.jpg)
![Cambridge International AS/A LevelMay/June 2015 9701 22 Mark Scheme Syllabus Paper Mark Scheme Mark Total name of particle relative mass relative charge proton electron neutron 1/1836 +1 1 [1] [1] [1] [1] [3] [1] [2] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [3] [2] [2] [2] [1] [4] Page 2 Question (a) (b) (i) Mass of an atom(s) relative to 1 / 12th (the mass) of (an atom of) carbon-12 OR relative to carbon-12 which is (exactly) 12 (ii) % of third isotope = 10 (24 79) 11.0) 10x (26100 24.3 10x = 248 x = 24.8 (3s.f.) (c) (i) 2Cl Cl2 + 2e anode cathode Mg2+ + 2e Mg (ii) Mg 31.65 24.3 20.84 16 H 1.31 Cl 46.2 35.5 1.30 1.30 1.31 1.30 = 1:1:1:1 MgOHCl (d) (i) Na2O basic / alkaline; Al2O3 amphoteric / acidic and basic; SO3 acidic Na2O (giant) ionic AND SO3 (simple / molecular) covalent (ii) Na2O + 2HCl 2NaCl + H2O Al2O3 + 6HCl 2AlCl3 + 3H2O Al2O3 + 2NaOH + 7H2O 2NaAl(OH)4(H2O)2 OR Al2O3 + 2NaOH + 3H2O 2NaAl(OH)4 OR Al2O3 + 2NaOH 2NaAlO2 + H2O OR Al2O3 + 2OH + 7H2O 2[Al(OH)4(H2O)2] Al2O3 + 2OH + 3H2O 2[Al(OH)4] OR Al2O3 + 2OH 2AlO2 + H2O SO3 + NaOH NaHSO4 OR SO3 + 2NaOH Na2SO4 + H2O ORCambridge International Examinations 2015<br />
Page 3 Question Cambridge International AS/A LevelMay/June 2015 9701 22 Mark Scheme Syllabus Paper Mark Scheme Mark Total [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [18] [2] [2] [3] [3] [1] [2] [2] [1] [1] [1] [18] [1] [1] [1] [1] [3] [1] (a) (i) 2PbS + 3O2 2PbO + 2SO2 reagents and formulae balancing (ii) S (is oxidised) 2 to (+)4 O (is reduced) 0 to 2 (b) (i) T = 400600 C (chosen as a compromise because) High T increases rate ora High T decreases yield / moves eqm left / makes less SO3 as forward reaction exothermic ora (ii) High pressure increases rate as collision frequency increases ora High pressure moves eqm right / favours forward reaction as more moles on left ora Uneconomic to use high pressures / high yield at low pressure (c) (i) Reaction (too) exothermic / acid spray produced (ii) SO3 + H2SO4 H2S2O7 H2S2O7 + H2O 2H2SO4 (d) Preservative owtte antimicrobial / antioxidant / reducing agent (e) (i) 12.350.01 / 1000 = 1.23510 4 (ii) 1.23510 41000 / 50 = 2.4710 3 (iii) 2.4710 364.1 = 0.158327 g = 158 (3 sf only) (a) (i) Bond breaking = Cl-Cl = 242 C-H = 410 = 652 kJ Bond forming = C-Cl = 340 Enthalpy change = 652771 = 119 H-Cl = 431 = 771 kJ (ii) UV / High T / sunlightCambridge International Examinations 2015<br />](https://learnah.org/wp-content/uploads/2018/08/June_2015_v2_MS_-_Paper_2_CIE_Chemistry_A-level_1-0.jpg)
