EXAM QUESTIONS

Question 1

Explain the differences between structural isomerism and stereoisomerism.

Use examples to show how compounds with the molecular formula C₄H₈ exhibit stereoisomerism and the three types of structural isomerism. [6 marks]

Answer 1

STRUCTURAL ISOMERISM:
> Same molecular formula, different structural formula
> Includes chain isomerism - butene & methylpropane have dif carbon skeleton/chain
> Includes position isomerism - but-1-ene & but-2-ene have dif position of C=C
> Includes functional group isomerism - butene & cyclobutane have dif functional group

STEREOISOMERISM:
> Same molecular formula and structural formula, different arrangement of atoms in space
> Includes only alkenes with C=C - lack of free rotation
> Split into E/Z isomers
> you can have Z-but-2-ene or E-but-2-ene

Question 2

A molecule of hydrocarbon Y can be thermally cracked to form one molecule of pentane and two molecules of ethene only.

(a) Deduce the molecular formula of Y
(b) State why high temperatures are necessary for cracking reactions to occur.
(c) Give one reason why thermal cracking reactions are carried out in industry.

Answer 2

(a) C₉H₂₀

(b) To break the C-C and/or C-H bonds

(c) To make products which are in HIGHER DEMAND / to make alkenes

Question 3

BANGING exam questions…

https://www.revisely.co.uk/alevel/chemistry/aqa/questions/introduction-to-organic-chemistry/isomerism-1