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Edexcel Jun 2014 (IAL) Paper 1 Q22
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![Mar k Acceptable Answers Reject energy required / energy needed / energy it takes from one mole of gaseous ions (no 2nd mark) Just from gaseous elements (no 2nd mark) (The energy / enthalpy change / released that accompanies the formation of) one mole of a(n ionic) compound (1) ALLOW as alternative for compound: lattice /crystal / substance / solid / product / salt from (its) gaseous ions (1) IGNORE References to standard conditions or any incorrect standard conditions ALTERNATIVE RESPONSE If no mark(s) already awarded from above, can answer by giving:- energy change per mole / enthalpy change per mole (1) (1) Li+(g) + F(g)LiF(s) NOTE If lattice energy of dissociation is given (e.g. energy required to break down 1 mol of an ionic lattice into its gaseous ions) max (1) for the 2nd scoring point gaseous ions WCH0101 1406 Question Number 22(a)<br />
Reject Mar Question Number 22(b)(i) Acceptable Answers Box 4 Box 3 Box 2 Box 1 Box 6 (Li+(g) + F-(g)) Box 5 Li+(g) + F(g) + e- Li+(g) + F2(g) + e- Li(g) + F2(g) Li(s) + F2(g) (LiF(s)) IGNORE missing electrons / e First mark (Box 1): Li(s) + F2(g) Second mark (Box 4): Li+(g) + F(g) (+e) (1) (1) Third and Fourth marks (if box 1 is correct): Box 2 as above i.e. Li(g) + F2(g) as above (1) Box 3 as above i.e. Li+(g) + F2(g) (+ e) as above (1) OR Box 2 Li(s) + F (g) (1) Box 3 Li(g) + F(g) (1) OR Box 2 Li(g) + F2(g) (1) Box 3 Li(g) + F(g) (1) WCH0101 1406<br />
Penalise use of Fl instead of F once only If Box 1 is INCORRECT max (2) for correct transitions e.g if use F(g) or F2(g) instead of F2(g), then 2 marks available for two correct transitions involving lithium. Question Number 22(b)(ii) FIRST, CHECK THE FINAL ANSWER Acceptable Answers Mark Reject WCH0101 1406 IF answer = 1046 (kJ mol1) then award (2) marks, with or without working Otherwise look for 616 = (+159) + (+520) + (+79) + (328) + HLE OR HLE = 616[ (+159) + (+520) + (+79) + (328)] (1) = 616430 = 1046 (kJ mol1) (1) NOTE ALLOW for 1 mark: (+)1046 (wrong sign) 186 (+430 instead of 430) (+)186 (+616 instead of 616) 1006.5 (+79 halved to +39.5) 1702 (wrong sign for 328)<br />
Acceptable Answers Question Number *22(c)(i) ALLOW reverse argument where appropriate (NaF more negative than NaCl because) First mark F smaller (than Cl) ALLOW fluorine ion is smaller (than a chlorine ion) OR F larger charge density (than Cl) (1) Second mark: F (forms) stronger (electrostatic) attractions (than Cl) IGNORE just stronger (ionic) bonds (1) Penalise ONCE ONLY in (c)(i) and (c)(ii) the use of the word atom(s) or molecule(s)/ use of just formulae such as Mg, Na, F, F2, Cl, Cl2, etc. OR Penalise ONCE ONLY in (c)(i) and (c)(ii) the use of words such as just magnesium (instead of magnesium ions/Mg2+) and/or just fluorine (instead of fluoride ions/F) /and or just chlorine (instead of chloride ions/Cl) IGNORE Any comments about polarization of the anion (by the cation) / covalent character Mark Reject NaF is smaller than NaCl F has a smaller atomic radius than Cl WCH0101 1406<br />
Question Number *22(c)(ii) Acceptable Answers Mark Reject MgF2 is smaller than NaF Mg2+ has a smaller atomic radius than Na+ ALLOW reverse argument where appropriate (NaF less negative than MgF2 because) First mark - size: Mg2+ smaller (than Na+) OR Magnesium ion is smaller (than Na+) (1) Second mark - charge: Mg2+ has a greater charge (density) (than Na+) OR Magnesium ion has a greater charge (density) (than Na+) (1) [NOTE: It follows that the statement that Mg2+ ions are smaller than Na+ ions would score BOTH marks] IGNORE Any comments about polarization of the anion (by the cation) / covalent character (Total for Question 22 = 12 marks) WCH0101 1406<br />](https://learnah.org/wp-content/uploads/2018/08/June_2014_IAL_MS_-_Unit_1_Edexcel_Chemistry_A-level_22-0.jpg)
