(must be stated, not transferred by inference from (ii) (1) 2 (ii) Na+(g) + Cl–(g) ® NaCl(s) allow NaCl(s) ® Na+(g) + Cl–(g) if definition reversed 1 (1) (iii) larger (cations) not atoms, Li, Na (1) same charge on the cation / ratio of charge:size decreases / lower charge density not effective nuclear charge (1) therefore weaker attractions between cation and anion (1) (must clearly mean attraction between cation and anion) 3 (iv) (cations) not atoms, Mg, Na allow this mark if from (iii) (1) ‘repeated error’ greater charge on the Group 2 cation / ratio of charge: size increases / higher charge density (1) therefore stronger attractions between cation and anion (1) (must clearly mean attraction between cation and anion) 3 [9] 4. (i) CaCl2(s) Ca2+ (aq) + 2Cl- (aq) (1)  Ca2+ (g) + 2Cl– (g)  CaCl2(s) (1) Ca2+(g)  Ca2+ (aq) (1) State symbols must be shown (ii) mol–1 H/kJ CaCl2 (s)  Ca2+ (aq) +2Cl– (aq) –123 Ca2+ Ca2+(g) +1650  (aq) Ca2+ 2Cl– CaCl2 (s)  –2255 (g) + (g) 2Cl– 2Cl–  –728 (g) (aq) Hhyd (Cl–(g) = = kJ mol–1 –364 3 equations (3) answer (1) OR via cycle: 3 steps (3) answer (1) 7 [7] (a) Steam condenses to water when 0 5. G  (1) = TS H (1)
(must be stated, not transferred by inference from (ii) (1) 2 (ii) Na+(g) + Cl–(g) ® NaCl(s) allow NaCl(s) ® Na+(g) + Cl–(g) if definition reversed (1) 1 (iii) larger (cations) not atoms, Li, Na (1) same charge on the cation / ratio of charge:size decreases / lower charge density not effective nuclear charge (1) therefore weaker attractions between cation and anion (1) (must clearly mean attraction between cation and anion) 3 (iv) (cations) not atoms, Mg, Na allow this mark if ‘repeated error’ from (iii) (1) greater charge on the Group 2 cation / ratio of charge: size increases / higher charge density (1) therefore stronger attractions between cation and anion (1) (must clearly mean attraction between cation and anion) 3 [9] 4. (i) CaCl2(s)  Ca2+ (aq) + 2Cl- (aq) (1) Ca2+ (g) + 2Cl– (g)  CaCl2(s) (1) Ca2+(g)  Ca2+ (aq) (1) State symbols must be shown (ii) H/kJ mol–1 CaCl2 (s)  Ca2+ (aq) +2Cl– (aq) –123 Ca2+ (aq)  Ca2+(g) +1650 Ca2+ (g) + 2Cl– (g)  CaCl2 (s) –2255 2Cl– (g)  2Cl– (aq) –728 Hhyd (Cl–(g) = = –364 kJ mol–1 3 equations (3) answer (1) OR via cycle: 3 steps (3) answer (1) 7 [7] 5. (a) Steam condenses to water when G  0 (1) H = TS (1)
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