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Edexcel Jun 2009 Paper 2 Q22
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![Correct Answer Between 150180 (K) Accept a range within the range e.g. 150-170 Correct Answer Because propanone has both polar and non polar characteristics/can form both London forces and H bonds/can form London forces and dipole-dipole forces OWTTE (1) London forces can be described as Van der Waals VDW Temporary dipole-dipole Instantaneous dipole-induced dipole Correct Answer Water: Hydrogen bonds with the (oxygen of the) carbonyl group/H bonds to the oxygen (1) Octane: London forces with methyl groups/carbon chain/CH groups/ H atoms (1) Both forces given allow (1) Reject C Reject Reject Carbon atoms Correct Answer Use of heat (1) To break down (a reactant)/one reactant into more than one product (1) Correct Answer CaCO3(s)CaO(s) + CO2(g) Allow correct multiples Reject Reject Mark Mark Mark Mark Mark Question Number 21 (a)(iii) Question Number 21 (b)(i) Question Number 21 (b)(ii) Question Number 22 (a)(i) Question Number 22 (a)(ii)<br />
Mark Mark Mark Mark Correct Answer Reject Group 2 carbonates are more (thermally) stable as you go down the group (1) as the cations get bigger/charge density gets less/cation has more shells (1) So have less of a polarising effect/distortion on the carbonate (ion)/less of a weakening effect on CO (1) 2nd and 3rd marks cq on first Metal gets bigger/element gets bigger Carbonate molecule Correct Answer orange Reject Yellow Any colour in conjunction with orange Correct Answer Reject (18.0/1000 x 0.100) = 1.8 x 103 /0.0018/2 x 103/0.002 IGNORE sf and units even if incorrect Reject Correct Answer (50/1000 x 0.100) = 5 x 103 (1) [If candidate fails to divide by 1000 in both (b)(ii) and b(iii) penalise only once] Moles HCl reacted = 3.2 x 103 (can get first mark here if 5 x 103 not shown above) So moles CaO = 1.6 x 103 (1) IGNORE sf Allow TE from b (ii) Question Number 22 (a)(iii) Question Number 22 (b)(i) Question Number 22 (b)(ii) Question Number 22 (b)(iii)<br />
Mark Correct Answer Reject Any % purity without 3 sf for second mark Mass CaO = (1.6 x 103 x 56.1) = 0.0898 g (1) % purity = 0.0898/0.121 x100 = 74.2% (1) OR Allow % calculated in terms of moles e.g moles of CaO should be 0.121 x 56.1 = 0.0021568 (mol) (1) % purity = 0.0016/0.0021568 = 74.2% (1) Accept = (1.6 x 103 x 56) = 0.0896 g (1) % purity = 0.0896/0.121 x100 = 74.0% (1) Allow TE of incorrect moles of CaO from (b)(iii) Allow TE from incorrect mass of CaO if answer is 100% 0.09 g and 74.4% is 1 out of 2 (rounding too soon) Correct Answer Reject (Clean) nichrome/platinum wire/ceramic rod/silica/nickel/chrome rod (1) (In conc.) HCl/HCl(aq)/dilute HCl (1) Heat/place in (blue Bunsen) flame (1) Metal loop/inoculating loop/glass rod/silver/spatula Place in yellow Bunsen flame/burn Correct Answer Barium/Ba/Ba2+ Reject Mark Mark Question Number 22 (b)(iv) Question Number 22 (c)(i) Question Number 22 (c)(ii)<br />](https://learnah.org/wp-content/uploads/2018/08/June_2009_MS_-_Unit_2_Edexcel_Chemistry_A-level_22-0.jpg)
