SPS F108 12.1_Carbonyl Compounds, Carboxylic Acids, Esters & Polyesters_A level_OCR_Chemistry_Marking Scheme 1
Carbonyl Compounds,
Carboxylic Acids,
... [Show More] Esters & Polyesters
Mark Scheme 1
Level A Level
Exam Board OCR
Sub-Topic
Time Allowed: 86 minutes
Score: /71
Percentage: /100
Grade Boundaries:
A* A B C D E U
>85% 77.5% 70% 62.5% 57.5% 45% <45%
Question Answer Mark Guidance
1 (a) (Relative) solubility (in stationary phase) 1 ALLOW how well the compound dissolves
IGNORE retention time AND partition
DO NOT ALLOW adsorption OR absorption
(b) (i) Compound B AND
M+/molecular ion peak (at m/z) = 124 1 ALLOW Mr = 124
IGNORE compound B because m/z = 124
ALLOW C7H8O + = 124 OR C7H8O2 = 124
2
ALLOW peak at (m/z =) 109 due to HOC6H4O+ ALLOW peak at (m/z =) 109 due to loss of CH3 IGNORE reference to other peaks in the spectrum
(ii) Compound (B) is less soluble in the stationary phase/ liquid 1 ORA
Answer refers to the first compound to emerge from the column
ALLOW compound (B) is more soluble in mobile phase/gas ALLOW compound interacts less with stationary phase/liquid OR compound interacts more with mobile phase/gas IGNORE compound adsorbs less
IGNORE compound is not very soluble (comparison needed)
IGNORE volatility OR reactivity
Question Answer Mark Guidance
(c) (i) reagent = K2Cr2O7 AND H2SO4
compound C =
ester =
3 ALLOW acidified dichromate
ALLOW H+/any acid
IGNORE concentration of acid
ALLOW Na2Cr2O7 /Cr2O 2- /(potassium OR sodium)
7
dichromate((VI))
-
ALLOW acidified MnO4
ALLOW Tollens’ reagent/ammoniacal silver nitrate
IGNORE conditions
ALLOW correct structural OR displayed OR skeletal formulae
OR a combination of above as long as unambiguous
ALLOW ECF from incorrect compound C
Check positions of OH groups
ALLOW esterification of phenol group
Question Answer Mark Guidance
(ii)
curly arrow from H– to Cδ+ dipole AND curly arrow from C=O bond to O correct intermediate AND curly arrow to H+
3 ANNOTATE ANSWER WITH TICKS AND CROSSES ETC
curly arrow must come from lone pair on H or negative charge on H
curly arrow must come from the bond, not the carbon atom
curly arrow must come from lone pair on O or negative charge on O and go to H or positive charge on H
Where circles have been placed round charges, this is for clarity only and does not indicate a requirement
ALLOW correct structural OR displayed OR skeletal formulae
OR a combination of above as long as unambiguous
ALLOW for second stage
IF H2O is used it MUST show the curly arrow from the negative charge or lone pair on the oxygen atom of the intermediate to H in H2O AND from the O—H bond to the O in H2O. Dipole not required on water molecule
Penalise missing –OH on intermediate only
IGNORE product – already given credit in part (i)
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