abc Mark Scheme Chemistry 6421 General Certificate of Education 2006 examination - January series CHM4 Further Physical and Organic Chemistry

Transcription

1 General ertificate of Education abc hemistry 642 M4 Further Physical and rganic hemistry Mark Scheme 2006 examination - January series Mark schemes are prepared by the Principal Examiner and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation meeting attended by all examiners and is the scheme which was used by them in this examination. The standardisation meeting ensures that the mark scheme covers the candidates responses to questions and that every examiner understands and applies it in the same correct way. As preparation for the standardisation meeting each examiner analyses a number of candidates scripts: alternative answers not already covered by the mark scheme are discussed at the meeting and legislated for. If, after this meeting, examiners encounter unusual answers which have not been discussed at the meeting they are required to refer these to the Principal Examiner. It must be stressed that a mark scheme is a working document, in many cases further developed and expanded on the basis of candidates reactions to a particular paper. Assumptions about future mark schemes on the basis of one year s document should be avoided; whilst the guiding principles of assessment remain constant, details will change, depending on the content of a particular examination paper. opyright 2006 AQA and its licensors. All rights reserved.

2 M4 AQA GE Mark Scheme, 2006 January series M4 SETIN A Question (a) exp exp exp x (3.0 x 0 ) (.0 x 0-3 ) 2000 mol -2 dm 6 s - Total 6 Question 2 (a) (i) [ + ][ - ] - log [ + ] [ + ] = [ - ] (iii) ( ) 0.5 = (iv) [+] = 4.02 x x 0-3 ( = 4.02 x 0 - ) p = 0.40 (i) Ka = [+][32-] [32] Ka = [+] [32] [+] = ( ) 0.25 ( = ) p =

3 AQA GE Mark Scheme, 2006 January series M4 (c) (i) ( ) 0.25 = ( ) - ( ) = (iii) mol salt formed = ( + ) = Ka x [ 3 2 ] [ ) = (.35 x 0-5 ) x (5.25 x 0-3 ) / V (.0 x 0-3 ) / V ( = x 0-5 ) p = 4.5 Total 6 Question 3 (a) (i) + 3D 2A + B mol dm -3 (iii) (forward reaction is) exothermic or more products formed (i) for N 2 4 Mr = 92.0 Mol = = mol N 2 4 reacted = = mol N 2 formed = (iii) Kc (N 2 ) = 2 (N2 4 ) (0.44/6) = 2 (0.8/6) = (iv) move to N 2 / to right / forwards none Total 2 3

4 M4 AQA GE Mark Scheme, 2006 January series Question 4 (a) nucleophilic addition M2 M N N M M3 4 (i) 2-hydroxybutanenitrile 3 N 2 () () (allow for amide even if not 4 7 N, i.e. RN 2 ) (if not amide, allow one for any isomer of 4 7 N which shows geometric isomerism) 2 (c) (i) (iii) 3 = Total 4

5 AQA GE Mark Scheme, 2006 January series M4 Question 5 (a) dimethylamine nucleophilic substitution M M 3 3 N 2 3 Br 3 N 3 M 2 M 4 3 N 2 4 (c) quaternary ammonium salt (cationic) surfactant / bactericide / detergent / fabric softener or conditioner/ hair conditioner (d) 3 N N 3 (allow 3 or 3 - N 4 + ) Total 0 Question 6 (a) polyamide or nylon (2,4) (allow nylon without numbers but if numbers are present they must be correct) condensation 3 N 2 (c) ionic bonding in aminoethanoic acid stronger attractions than ydrogen bonding in hydroxyethanoic (can only score if includes that aminoethanoic is ionic) (e.g. stronger ydrogen bonding in aminoethanoic acid scores 0) (mention of electrostatic forces between molecules scores 0) Total 5 5

6 M4 AQA GE Mark Scheme, 2006 January series SETIN B Question 7 (a) ethyl benzene chloroethane or bromoethane (or ethene and hydrogen chloride/bromide) aluminium chloride/bromide or iron(iii) chloride /bromide or iron + chorine/bromine 3 2 l + All All 4 - electrophilic substitution M2 structure M M3 arrow Question l / propanoyl chloride or ( 3 2 ) 2 / propanoic anhydride NaB 4 or LiAl 4 or 2 /Ni (not Sn/Fe with l) Total (a) (i) 3 peaks or shown in a list m/z = 26, 28 and 30 (56 +70/72/74) (all 3 scores 2) 2 (if 56 wrong allow (x + 70/72/74) for (x cannot be zero) (any two scores ) [ 4 8 l 2 ] 3 2 l + 2 l () () () 3 allow wrong structure for structure dot can be anywhere 6

7 AQA GE Mark Scheme, 2006 January series M4 (i) optical equal mixture of enantiomers (optically) inactive or effects cancel plane polarised light use stereospecific reagent (QoL) rotated in opposite/different directions (QoL) reacts with one isomer only carbocation planar - (must refer to carbocation or intermediate) attack from either side equally likely (must refer to carbocation /intermediate) (c) (i) 2 peaks (if 4 peaks allow splitting only) ratio 6:2 or 3: doublet (6 or 3) quartet (2 or ) 7 max S 3 l l 2 3 T l l Total 9 7