Mark Scheme
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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS
GCE Ordinary Level
e ap .c rs om
MARK SCHEME for the May/June 2011 question paper for the guidance of teachers
5070 CHEMISTRY
5070/21 Paper 2 (Theory), maximum raw mark 75
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes must be read in conjunction with the question papers and the report on the examination.
• Cambridge will not enter into discussions or correspondence in connection with these mark schemes.
Cambridge is publishing the mark schemes for the May/June 2011 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.
Page 2
Mark Scheme: Teachers’ version GCE O LEVEL – May/June 2011
Syllabus 5070
Paper 21
A1 Allow correct name but formula takes precedence (a) V2O5 (1) (b) ZnSO4 (1) (c) AgI (1) (d) CF3Cl3 (1) (e) (NH4)2SO4 / ZnSO4 (1) (f) CH4 (1) (g) (NH4)2SO4 (1) [1] [1] [1] [1] [1] [1] [1] [Total: 7] A2 (a) sulfur dioxide (1) Allow SO2 (b) copper(II) sulfate (1) Allow CuSO4 (c) H+ + OH– → H2O (1) Ignore state symbols (d) (i) Copper(II) hydroxide (1) Allow Cu(OH)2 (ii) Cu2+(aq) + 2OH–(aq) → Cu(OH)2(s) Balanced equation (1) Correct state symbols (1)
[1]
[1]
[1]
[1]
[2]
(e) Mol ratio Cu:O = CuO (1)
79.9 20.1 : / 1.25 : 1.26 (1) 64 16
[2] [Total: 8]
© University of Cambridge International Examinations 2011
Page 3
Mark Scheme: Teachers’ version GCE O LEVEL – May/June 2011
Syllabus 5070
Paper 21 [1] [1]
A3 (a) (i) same number of electrons / same number of protons / same electronic arrangement of electrons / both have
UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS
GCE Ordinary Level
e ap .c rs om
MARK SCHEME for the May/June 2011 question paper for the guidance of teachers
5070 CHEMISTRY
5070/21 Paper 2 (Theory), maximum raw mark 75
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes must be read in conjunction with the question papers and the report on the examination.
• Cambridge will not enter into discussions or correspondence in connection with these mark schemes.
Cambridge is publishing the mark schemes for the May/June 2011 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.
Page 2
Mark Scheme: Teachers’ version GCE O LEVEL – May/June 2011
Syllabus 5070
Paper 21
A1 Allow correct name but formula takes precedence (a) V2O5 (1) (b) ZnSO4 (1) (c) AgI (1) (d) CF3Cl3 (1) (e) (NH4)2SO4 / ZnSO4 (1) (f) CH4 (1) (g) (NH4)2SO4 (1) [1] [1] [1] [1] [1] [1] [1] [Total: 7] A2 (a) sulfur dioxide (1) Allow SO2 (b) copper(II) sulfate (1) Allow CuSO4 (c) H+ + OH– → H2O (1) Ignore state symbols (d) (i) Copper(II) hydroxide (1) Allow Cu(OH)2 (ii) Cu2+(aq) + 2OH–(aq) → Cu(OH)2(s) Balanced equation (1) Correct state symbols (1)
[1]
[1]
[1]
[1]
[2]
(e) Mol ratio Cu:O = CuO (1)
79.9 20.1 : / 1.25 : 1.26 (1) 64 16
[2] [Total: 8]
© University of Cambridge International Examinations 2011
Page 3
Mark Scheme: Teachers’ version GCE O LEVEL – May/June 2011
Syllabus 5070
Paper 21 [1] [1]
A3 (a) (i) same number of electrons / same number of protons / same electronic arrangement of electrons / both have