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Edexcel Jun 2009 Paper 1 Q23
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![Question Number 22 (c) QWC Question Number 23 (a) Mark ions get bigger (down Group) Correct Answer Reject Any two of the following: (outermost) electron further from the nucleus/atoms get bigger/more shells (outermost) electron more shielded (by inner shells of e-) (force of) attraction between nucleus and (outermost) electron decreases (down the Group) OR (outermost) electron held less strongly (down the Group) OR (outermost) electron becomes easier to remove (down the Group) IGNORE any references to(effective) nuclear charge or more protons. Reject Mark Correct Answer element structure bonding sodium Giant metallic silicon Giant (atomic)/ macromolecular/ giant molecular covalent sulfur simple / small molecules OR (simple) molecular OR S8 molecules covalent or van der Waals forces/ London forces/ intermolecular forces/dispersion forces/induced- dipole forces IGNORE the word lattice OR crystalline 6 boxes correct (3) 5,4 boxes correct (2) 3,2 boxes correct (1) 1,0 boxes correct (0)<br />
Question Number 23 (b) Question Number 23 (c) QWC Mark Mark Correct Answer Reject Si : covalent bonds / many bonds/ strong bonds (between atoms) (1) S : weak forces /van der Waals forces/London forces/dispersion forces/intermolecular forces/induced-dipole forces (1) (need to be overcome) any reference to intermolecular forces in Si suggestion that covalent bonds are broken Correct Answer Reject atoms decrease in size any mention of molecules/ covalent bonds/ van der Waals forces/ ionic bonds (0) overall Cations/ions decrease in size (from Na+ to Al3+) OR charge increases/charge density on (cat)ions increases/ effective nuclear charge increases (from Na+ to Al3+) (1) more e (per atom in sea of delocalized electrons) / more delocalized electrons OR (force of) attraction between (cat)ions/nucleus and (delocalised) electrons increases (from Na to Al) IGNORE nuclear charge increases/ increasing no. of protons (1)<br />
Question Number 23 (d)(i) QWC Question Number 23 (d)(ii) Question Number 23 (e)(i) Correct Answer RejectAdd MgO to acid/react MgO with acid/dissolve MgO in acid (1) [NOTE: mention of heating not required. IGNORE water bath/reflux]Filter (1)Heat/boil filtrate /MgSO4 solution (until volume reduced by half) (1)Leave to cool/leave to crystallise/evaporate slowly/leave to evaporate (1) (decant / filter / pick out crystals, then) Leave to dry/pat dry/dry between filter papers/put in an oven/put in a desiccator/dry the crystals (1) IGNORE any washing of crystals immediately prior to drying them Just warm the filtrate/MgSO4 solution Use of a desiccant (added to crystals) Correct Answer Reject Rinse with (plenty of) water /use a damp cloth or damp (paper) towel / add a (named) weak alkali (e.g. solid or aqueous sodium hydrogencarbonate) Correct Answer Insoluble strontium sulfate/insoluble SrSO4 (forms on the strontium carbonate) Any named strong alkali/just strong alkali Reject Mark Mark Mark<br />
Reject Reject Reject Reject Mark Mark Mark Mark Question Number 23 (e)(ii) Question Number 24 (a)(i) Question Number 24 (a)(ii) Question Number 24 (a)(iii) Correct Answer 2 (aq)SrSO4(s) Sr2+(aq) + SO4 species (1) state symbols (1) 2nd mark is cq on first mark Sr2+(aq) + 2Cl(aq) + 2Na+(aq) + SO4 2Na+(aq) scores (1) SrCl2(aq) + Na2SO4(aq) (cid:198) SrSO4(s) + 2NaCl(aq) scores (1) 2(aq)SrSO4(s) + 2Cl(aq) + Correct Answer 2.90 = 0.05(00) (mol) 58 correct answer only (1) Correct Answer 200 x 4.18 x 58.2 = 48655 (J) OR 48.655 kJ (1) for correct T(1) IGNORE sf IGNORE signs at this stage Correct Answer48655 = 973 100 (J mol-1) 0.0500 = 973 kJ mol-1 (3 s.f.) / 973000 J mol-1 (3 s.f.) answer (1) sign and units (1) [Do not award sign and units mark if units given are just kJ or just J] three sig figs (1) CQ on (a)(i) & (ii)<br />](https://learnah.org/wp-content/uploads/2018/08/June_2009_MS_-_Unit_1_Edexcel_Chemistry_A-level_23-0.jpg)
