Organic ChemistryCambridge IGCSE Chemistry: Topic test

20 questions, 54 marks

Cambridge IGCSE Chemistry

Organic Chemistry topic test

Total 54 marks

Name

Class

Date

1
A haulage company runs a fleet of lorries on diesel oil, obtained by fractional distillation of crude oil. A driver notices that diesel does not catch fire as easily as the petrol used in the company's smaller vans, and that diesel is thicker and pours more slowly than petrol.
(a)
Crude oil is separated into fractions such as petrol and diesel oil by fractional distillation. Which statement correctly compares the hydrocarbon chains found in the petrol fraction with those found in the diesel oil fraction?
[1 mark]
APetrol contains longer hydrocarbon chains than diesel oil
BPetrol and diesel oil contain exactly the same chain lengths
CPetrol contains no hydrocarbons at all
DPetrol contains shorter hydrocarbon chains than diesel oil
(b)
Which property of diesel oil, compared with petrol, best explains why the driver finds it thicker and slower-pouring?
[1 mark]
ADiesel oil has a lower viscosity than petrol
BDiesel oil has a higher viscosity than petrol
CDiesel oil is a pure compound while petrol is a mixture
DDiesel oil has a lower boiling point than petrol
(c)
Suggest why diesel oil is less flammable (does not catch fire as easily) than petrol, and name one other named fraction of crude oil, stating one use for it.
[2 marks]
Total for question 1: 4 marks
2
A plastics manufacturer receives a delivery of a large alkane extracted from the diesel fraction of crude oil. Because there is little demand for such a large alkane as a fuel, the company heats it strongly over a hot catalyst to break it down into smaller, more useful molecules, including a gaseous alkene and a shorter alkane.
(a)
What is the name of the process the company uses to break the large alkane molecule down into smaller molecules?
[1 mark]
AFractional distillation
BPolymerisation
CCracking
DFermentation
(b)
The manufacturer tests the gaseous product by shaking a sample with aqueous bromine, which turns from orange to colourless. What does this confirm about the gas?
[1 mark]
AThe gas is saturated, showing it must be an alkane
BThe gas is unsaturated, showing it must be an alkene
CThe gas is an alcohol, since only alcohols decolourise bromine water
DThe gas contains no carbon atoms at all
(c)
The company reacts a sample of the alkene product with steam in the presence of an acid catalyst. Name the type of reaction taking place, and name the family of compound produced.
[2 marks]
Total for question 2: 4 marks
3
A chemistry class investigates the reaction of methane with chlorine gas. A test tube containing a mixture of methane and chlorine gas is left in a dark cupboard for a day, and no reaction is observed. An identical test tube is placed in bright sunlight, and within minutes a colourless gas containing carbon, hydrogen and chlorine forms, along with a second gas that turns damp litmus paper white then red before bleaching it.
(a)
Explain why no reaction occurs in the dark cupboard, but a reaction occurs when the mixture is placed in sunlight, and name the type of reaction taking place between methane and chlorine.
[3 marks]
(b)
Give the molecular formula of methane, and write a word equation for its reaction with chlorine to form the monosubstituted product described. State the name and one confirming test for the second gas produced.
[4 marks]
Total for question 3: 7 marks
4
A petrochemical technician is given two unlabelled gas cylinders, W and X, each containing a different pure hydrocarbon with four carbon atoms per molecule. Bubbling gas W through aqueous bromine leaves the orange colour unchanged, while bubbling gas X through aqueous bromine turns it from orange to colourless. Both gases burn completely in a plentiful supply of oxygen to form only carbon dioxide and water.
(a)
Identify, with reasons, whether gas W and gas X are more likely to be an alkane or an alkene, and give a possible molecular formula for each gas, given that each has four carbon atoms per molecule.
[6 marks]
(b)
Both gases burn completely in a plentiful supply of oxygen to form only carbon dioxide and water. Write a balanced symbol equation for the complete combustion of gas X (C4H8), and explain, in terms of bonding, why gas X is able to react with hydrogen in the presence of a nickel catalyst to form gas W, while gas W does not undergo the same reaction with hydrogen.
[6 marks]
Total for question 4: 12 marks
5
A drinks company ferments aqueous glucose solution using yeast, kept at 30°C with no air present, to produce ethanol for a fruit-based alcoholic drink. A rival production method used elsewhere reacts ethene gas directly with steam over an acid catalyst at high temperature and high pressure to produce ethanol instead.
(a)
Why must the fermentation of glucose by yeast be carried out in the absence of oxygen?
[1 mark]
AOxygen would react with the glucose to form carbon dioxide and water directly, wasting it
BOxygen would kill the yeast immediately, stopping the reaction
CYeast respires aerobically in the presence of oxygen, producing carbon dioxide and water rather than ethanol
DOxygen would evaporate the ethanol as soon as it formed
(b)
Which statement correctly compares fermentation with the catalytic addition of steam to ethene as methods of producing ethanol?
[1 mark]
AThe catalytic method uses a renewable raw material, while fermentation uses a non-renewable raw material
BBoth methods use exactly the same raw material and conditions
CFermentation requires very high pressure, while the catalytic method requires no pressure at all
DFermentation uses a renewable raw material (glucose from plants), while the catalytic method uses ethene from a non-renewable source (crude oil)
(c)
State one advantage of producing ethanol by the catalytic addition of steam to ethene, compared with producing it by fermentation.
[2 marks]
Total for question 5: 4 marks
6
A student is given a colourless liquid known to be ethanoic acid and tests its reactions. She adds a piece of magnesium ribbon to a sample, and separately adds a spatula of solid sodium carbonate to a second sample.
(a)
The student observes bubbles of gas forming when magnesium is added to the ethanoic acid. Which gas is produced, and what could be used to confirm its identity?
[1 mark]
AOxygen, confirmed with a glowing splint
BHydrogen, confirmed with a lighted splint, which produces a squeaky pop
CCarbon dioxide, confirmed with limewater
DChlorine, confirmed with damp litmus paper
(b)
The student then adds sodium carbonate to a second sample of ethanoic acid and sees vigorous fizzing. What is the correct name of the salt formed in this reaction?
[1 mark]
ASodium ethanoate
BSodium chloride
CSodium oxide
DMagnesium ethanoate
(c)
The student then mixes a sample of the ethanoic acid with ethanol and a few drops of concentrated sulfuric acid as a catalyst, and gently warms the mixture. Name the type of compound formed, and describe one property of this type of compound that makes it easily recognisable.
[2 marks]
Total for question 6: 4 marks
7
A packaging company manufactures thin plastic sheeting by joining together thousands of small ethene molecules, end to end, using high pressure and a catalyst, with no other product formed. The sheeting is later used to wrap food products before disposal in general waste.
(a)
Name the type of polymerisation used to make this plastic sheeting from ethene, name the polymer formed, and explain why no other product is formed alongside the polymer in this reaction.
[3 marks]
(b)
State one environmental challenge caused by disposing of the plastic sheeting in general waste after use, and explain why plastics made by addition polymerisation, like this one, tend to cause this problem more than natural materials such as paper.
[4 marks]
Total for question 7: 7 marks
8
A laboratory technician is given a bottle labelled only with the structural formula CH3CH2COOH, and a second bottle labelled only with the displayed formula of CH2=CHCH3, and must identify what type of compound each contains before using them in an experiment.
(a)
Identify the homologous series to which each compound belongs, giving a reason based on the functional group present in each structural or displayed formula, and give the correct name of each compound.
[6 marks]
(b)
State the general formula of the homologous series to which each compound belongs, and explain, using the idea of a homologous series, why propanoic acid and a carboxylic acid with one more carbon atom would be expected to have similar chemical properties but a different boiling point.
[6 marks]
Total for question 8: 12 marks

End of questions