Eduqas A-Level Chemistry (A410)
A-Level Chemistry
Answer sheet
Organic chemistry
Separate mark scheme — do not issue with the student worksheet
Time guide: — · Questions: 32 · Total marks: 104
Written in Eduqas A-Level style. Show working and include units.
Indicative marking points. Award marks for equivalent scientific or mathematical wording. Do not issue this sheet with the student worksheet.
1. State what is meant by a homologous series.
[1 mark]
- same functional group, differ by CH₂
2. State what is meant by isomerism.
[1 mark]
- same molecular formula, different structure
3. State what is meant by a nucleophile.
4. State what is meant by an electrophile.
5. State what is meant by free-radical substitution.
6. State what is meant by electrophilic addition.
7. State what is meant by nucleophilic substitution.
8. State what is meant by oxidation of alcohols.
[1 mark]
- primary → aldehyde → carboxylic acid; secondary → ketone
9. State what is meant by a carbonyl test.
[1 mark]
- Brady's / 2,4-DNP orange ppt
10. State what is meant by optical isomerism.
[1 mark]
- chiral carbon, four different groups
11. Jac is asked about a homologous series in a Eduqas Chemistry paper.
(a) [2 marks]
- gradual change in physical properties
12. Jac is asked about isomerism in a Eduqas Chemistry paper.
(a) [2 marks]
- structural and stereoisomerism
13. Jac is asked about a nucleophile in a Eduqas Chemistry paper.
14. Jac is asked about an electrophile in a Eduqas Chemistry paper.
(a) [2 marks]
- H⁺, Br⁺ (from Br₂/FeBr₃), NO₂⁺
(b) [3 marks]
- attacks electron-rich centres
15. Jac is asked about free-radical substitution in a Eduqas Chemistry paper.
(a) [2 marks]
- initiation, propagation, termination
16. Jac is asked about electrophilic addition in a Eduqas Chemistry paper.
17. Molecular formula of hexane
18. How many structural isomers of C₄H₁₀
20. Moles in 6.0 g of ethanoic acid
21. A chiral carbon is in CH₃CHBrCH₂CH₃. How many optical isomers
22. Percentage yield 7.2 g from theoretical 9.0 g
23. Jac carries out a Eduqas-style required practical linked to organic chemistry. This is a typical Eduqas required-practical style question.
(a) [2 marks]
- Independent: the independent variable for this topic
- Dependent: the measured outcome
(b) [2 marks]
- keep all other variables constant
- so the test is fair / only one variable is changed
(c) [2 marks]
- repeat and calculate a mean / use a tighter method
24. Jac carries out collecting valid data for organic chemistry. This is a typical Eduqas required-practical style question.
(a) [2 marks]
- Independent: a chosen factor
- Dependent: a quantitative measurement
(b) [2 marks]
- calibrated instrument
- so the test is fair / only one variable is changed
(c) [2 marks]
- systematic error from zero error
25. Jac carries out drawing a graph for organic chemistry. This is a typical Eduqas required-practical style question.
(a) [2 marks]
- Independent: x-variable
- Dependent: y-variable
(b) [2 marks]
- same scale / same apparatus
- so the test is fair / only one variable is changed
(c) [2 marks]
- not drawing a line of best fit through the trend
26. Jac carries out evaluating a method about organic chemistry. This is a typical Eduqas required-practical style question.
(a) [2 marks]
- Independent: method change
- Dependent: precision / accuracy
(b) [2 marks]
- same sample size
- so the test is fair / only one variable is changed
27. Compare a homologous series with isomerism.
[4 marks]
- same functional group, differ by CH₂
- same molecular formula, different structure
- give one linked difference
28. Compare isomerism with a nucleophile.
[4 marks]
- same molecular formula, different structure
- electron-pair donor
- give one linked difference
29. Compare a nucleophile with an electrophile.
[4 marks]
- electron-pair donor
- electron-pair acceptor
- give one linked difference
30. Compare an electrophile with free-radical substitution.
[4 marks]
- electron-pair acceptor
- alkanes + halogens in UV
- give one linked difference
31. Apply your knowledge of nucleophilic substitution to this situation: Sn1 or Sn2
32. Apply your knowledge of oxidation of alcohols to this situation: acidified dichromate