Edexcel IGCSE Chemistry 4 Organic chemistry Question Bank

Practise organic chemistry with formulae, displayed structures, crude oil fractions, reaction types, esters and polymer questions from Edexcel papers.

Covered syllabus points

(a) Introduction (b) Crude oil (c) Alkanes (d) Alkenes (e) Alcohols (f) Carboxylic acids (g) Esters (h) Synthetic polymers

[Maximum number: 11]

This question is about hydrocarbons.

(a)

State the meaning of the term hydrocarbon.

[ 2 ]

(b)

One homologous series of hydrocarbons is the alkanes.

Pentane $\left(\mathrm{C}_{5} \mathrm{H}_{12}\right)$ is an alkane.

[ 5 ]

(i)

Incomplete combustion can occur when the oxygen supply is limited.

Give the names of two products of the incomplete combustion of pentane.

1 ................................
2 ................................

[ 2 ]

(ii)

One of the products of incomplete combustion is a poisonous gas.

State why this gas is poisonous to humans.

[ 1 ]

(iii)

$\mathrm{C}_{5} \mathrm{H}_{12}$ has three isomers.

The displayed formula for one of these isomers is

Figure for Question (iii) — Edexcel IGCSE Chemistry

Draw the displayed formulae of the other two isomers.

[ 2 ]

- two correct displayed formulae for the other isomers of $\ce{C5H12}$

Marking guidance:
- Award the two structures in either order.
- Use the verified answer images for the displayed formulae.

(c)

Another homologous series of hydrocarbons is the alkenes.

Alkenes are unsaturated hydrocarbons.

[ 4 ]

(i)

Give the general formula for the alkenes.

[ 1 ]

(ii)

State the meaning of the term unsaturated.

[ 1 ]

(iii)

Describe a test to show that a hydrocarbon is unsaturated.

[ 2 ]

- add bromine water / bromine solution
- bromine water / solution is decolourised or turns from orange to colourless

Accept:
- $\ce{Br2(aq)}$
- add acidified potassium manganate(VII); it is decolourised / turns from purple to colourless

Ignore:
- clear

Reject:
- discoloured
- any incorrect initial colour

Marking guidance:
- If the initial colour of bromine water is given, it must be correct; allow any combination of orange / yellow / brown.
- The observation mark depends on adding bromine water or a near miss.

[Maximum number: 10]

Crude oil is a mixture of hydrocarbons.

(a)

Name the process used to separate crude oil into fractions.

[ 1 ]

(b)

Give one use of the kerosene fraction.

[ 1 ]

(c)

One of the hydrocarbons in the refinery gas fraction is an alkane with the structural formula $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}$

[ 1 ]

(i)

Give the name of this alkane.

[ 1 ]

(d)

One of the alkanes in the gasoline fraction has the displayed formula

Figure for Question (d) — Edexcel IGCSE Chemistry

[ 2 ]

(i)

Determine the molecular formula of this alkane.

[ 1 ]

$\ce{C7H16}$

(ii)

Give the general formula for the alkanes.

[ 1 ]

(e)

Catalytic cracking is used to convert long-chain alkanes into shorter-chain alkanes.

[ 3 ]

(i)

Name the catalyst used in catalytic cracking.

[ 1 ]

alumina / silica

Accept:
- aluminium oxide
- silicon dioxide
- $\ce{Al2O3}$
- $\ce{SiO2}$
- zeolite(s)
- aluminosilicate(s)

(ii)

Explain why it is necessary to convert long-chain alkanes into shorter-chain alkanes.

[ 2 ]

(f)

Catalytic cracking also produces alkenes.
$\ce{C11H24}$ can undergo cracking to give pentane ( $\ce{C5H12}$ ) and two different alkenes.
Complete the equation for this cracking reaction.

$\ce{C11H24}$ -> $\ce{C5H12}$ + ................................ + ................................

[ 2 ]

$\ce{C11H24 -> C5H12 + C2H4 + C4H8}$

Marking guidance:
- Alkenes can be in either order.
- 1 mark for $\ce{C2H4}$ .
- 1 mark for $\ce{C4H8}$ .

Allow:
- $\ce{C6H12}$ / $\ce{2C3H6}$ / $\ce{C3H6}$ + $\ce{C3H6}$ for 1 mark
- correct displayed formulae

[Maximum number: 15]

Alcohols contain the functional group - OH

(a)

Give the structural formula of the alcohol that contains one carbon atom.

[ 1 ]

$\mathrm{CH}_{3} \mathrm{OH}$

IGNORE displayed
formula

1
grad

(b)

Ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ is an alcohol that can be obtained from glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ .

[ 5 ]

(i)

Name the process that converts glucose into ethanol.

[ 1 ]

(ii)

Explain why this process is carried out in the absence of air and at a temperature below $40^{\circ} \mathrm{C}$ .

[ 4 ]

Explanation including four from

M1 fermentation/reaction/respiration needs to be anaerobic

M2 because in air / aerobic conditions ethanol not produced

M3 because in air / aerobic conditions $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$ are produced

M4 (if temperature above $40^{\circ} \mathrm{C} /$ too high) enzymes (in yeast) become denatured/lose their structure OWTTE

M5 causing fermentation/reaction to slow down /stop

ALLOW M1 in air ethanol would react with oxygen / be oxidised

M2 in air ethanol would form ethanoic acid /carboxylic acid/vinegar

4
exp

(c)

The table gives information about some organic compounds in the same homologous series.

Table for Question (c) — Edexcel IGCSE Chemistry

[ 4 ]

(i)

Complete the table by giving the missing information.

[ 3 ]

Figure for Answer to Question (i) — Edexcel IGCSE Chemistry

M2 $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}_{2}$

M3 butanoic acid

3
grad

(ii)

Name the homologous series that contains these compounds.

[ 1 ]

(d)

The compounds in the table can react with alcohols to form esters.

When preparing esters, a small amount of concentrated sulfuric acid is also used.

[ 5 ]

(i)

State the purpose of the acid.

[ 1 ]

(ii)

Draw the displayed formula of the ester that forms when propanoic acid reacts with ethanol.

[ 2 ]

(iii)

Esters have particular uses that depend on their properties.

Give an example of a property and use of esters.
property
use

[ 2 ]

[Maximum number: 9]

This question is about alcohols, carboxylic acids and esters.

(a)

Ethanol can be manufactured by the fermentation of a solution of glucose.

[ 4 ]

(i)

Write a word equation for this reaction.

[ 1 ]

(ii)

State the substance that needs to be added for the reaction to occur.

[ 1 ]

(iii)

State two conditions needed for this reaction.

1
2

[ 2 ]

(b)

In the presence of an acid catalyst, ethanoic acid is heated with butanol to form an ester.

[ 3 ]

(i)

Which of these is the formula of the ester?

$\mathrm{CH}_{3} \mathrm{COOC}_{3} \mathrm{H}_{7}$

$\mathrm{CH}_{3} \mathrm{COOC}_{4} \mathrm{H}_{9}$

$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{COOC}_{4} \mathrm{H}_{9}$

$\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COOC}_{2} \mathrm{H}_{5}$

[ 1 ]

(ii)

State how you would know that an ester has formed.

[ 1 ]

(iii)

Give one use of an ester.

[ 1 ]

(c)

Aspirin is a compound used to reduce pain．
Aspirin contains a carboxylic acid functional group and an ester functional group．

[ 2 ]

(i)

（i）State what is meant by the term functional group．

[ 1 ]

(ii)

This is the structural formula of aspirin.

Figure for Question (ii) — Edexcel IGCSE Chemistry

Draw a circle around the carboxylic acid functional group.

[ 1 ]

All question bank results loaded

Covered syllabus points

4 Organic chemistry question 1

Question (a)

Question (b)

Question (i)

Question (ii)

Question (iii)

Question (c)

Question (i)

Question (ii)

Question (iii)

4 Organic chemistry question 2

Question (a)

Question (b)

Question (c)

Question (i)

Question (d)

Question (i)

Question (ii)

Question (e)

Question (i)

Question (ii)

Question (f)

4 Organic chemistry question 3

Question (a)

Question (b)

Question (i)

Question (ii)

Question (c)

Question (i)

Question (ii)

Question (d)

Question (i)

Question (ii)

Question (iii)

4 Organic chemistry question 4

Question (a)

Question (i)

Question (ii)

Question (iii)

Question (b)

Question (i)

Question (ii)

Question (iii)

Question (c)

Question (i)

Question (ii)