Q1.
Some fruits, seeds and nuts are sources of vegetable oils.
The table gives some information about three types of vegetable oil.
Corn oil
Olive oil
14.4 14.3 Saturated fat in %
Unsaturated fat in %
Melting point in °C
Smoke point in °C
81.2
−18 to −5
229 to 268
81.2
−12 to −6
204 to 210
Rapeseed oil
6.6
88.6
−10 to +5
230 to 240
The smoke point is the temperature range at which the oil begins to produce smoke when heated.
(a) Use information from the table above to answer these questions.
(i) Tick ( ) one correct reason why a vegetable oil has a range for the melting point.
Reason
A vegetable oil has a high percentage of unsaturated fat.
A vegetable oil has a range for the smoke point.
A vegetable oil has a mixture of fats.
Tick ( )
(ii) Complete the sentence.
The type of vegetable oil with the largest temperature range of smoke point is
..................................................................................... .
(b) Bromine water was added drop by drop to 5 cm
3
of each type of vegetable oil.
(i) Draw a ring around the correct answer to complete the sentence.
(1)
(1)

colourless.
The colour of the first drop of bromine water changes from orange to green. white.
(ii) Which type of vegetable oil will react with the most drops of bromine water?
Give a reason for your answer.
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(c) Potato slices can be boiled in water or fried in olive oil.
(1)
(i) Olive oil starts to produce smoke when heated to 204°C.
The smoke contains carbon particles.
Suggest what happens to molecules in olive oil to produce carbon particles.
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(1)
(ii) Potato slices boiled in water will be different from potato slices fried in olive oil.
Describe two differences.
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(2)
(Total 8 marks)

Q2.
There has been research into fuels for car engines.
Fuel Content
Meltingpoint in °C
Flashpointin
°C
Energy releasedin MJ per litre
Ethanol
Diesel
Petrol
C
2
H
5
OH −114 hydrocarbons About −24 hydrocarbons About −57
+14
+64
−45
21.2
38.6
34.8
Rapeseed oil fats About +5 +130 32.8
The flashpoint is the lowest temperature a fuel vapour ignites in air.
(a) The melting point of ethanol is precise but the other melting points are approximate.
Suggest why.
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(2)
(b) Ethanol is produced by fermentation of sugar cane. Rapeseed oil is produced by pressing rapeseeds. Waste plant material from both processes is used to feed animals.
(i) Describe how the process of fermentation is done.
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(2)
(ii) Carbon neutral fuels do not increase the amount of carbon dioxide in the atmosphere.
Suggest why using a biofuel, such as ethanol or rapeseed oil, is thought to be carbon neutral.
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(2)
(c) When any fuel from the table is used in a car engine, the exhaust gases contain nitrogen oxides.
Explain why.
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(2)
(d) Evaluate replacing petrol with ethanol as a fuel for cars.
To gain full marks you should give a justified conclusion.
Use the information from the table and your knowledge to answer this question.
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(4)
(Total 12 marks)

M1.
(a) (i) a vegetable oil has a mixture of fats 1
(ii) corn (oil) allow 229 to 268 (°C)
1
(b) (i) colourless
1
(ii) rapeseed (oil) 1 because this oil has most unsaturated fat or because this oil has the most carbon-carbon double bonds accept because this oil has least saturated fat allow this oil has more unsaturated fat ignore figures unless there is an indication that 88.6(%) is the highest percentage of unsaturated fat ignore melting points / smoke points if corn oil or olive oil is chosen then allow 1 mark for has a high amount / percentage of unsaturated fat or has a low amount / percentage of saturated fat 1
(c) (i) (olive oil / molecules) decompose / break down allow burn ignore react
1
(ii) any two from: for olive oil
• different flavour / taste
• high(er) energy content
• hard(er) / crisp(er) or different texture
• dark(er) / different colour
• have (more) fat
• cooks quick(ly) if answered in terms of water:
• different flavour / taste
• low(er) energy content
• soft(er) or different texture
• light(er)/ different colour
• have less / no fat
• cooks slow(ly) ignore healthier 2 [8]

M2.
(a) ethanol is made up of only one type of molecule or ethanol is a compound allow ethanol is pure 1 diesel / petrol / rapeseed oil are mixtures accept composition of diesel / petrol / rapeseed oil varies / changes allow different hydrocarbons have different melting points ignore diesel, petrol and rapeseed oil are impure 1
(b) (i) sugar is mixed with / dissolved in water accept sugar cane for sugar
1 yeast (is added) allow enzymes are added if no other mark awarded, allow correct word or chemical equation for 1 mark
1
(ii) (growing sugar cane / rapeseed) plants absorbs carbon dioxide accept carbon for carbon dioxide accept carbon dioxide is used for photosynthesis 1 which is released (when the biofuel burns) do not accept no carbon dioxide is released (when biofuels burn)
1
(c) nitrogen / N
2 and oxygen / O
2
(in the air) do not accept fuels contain nitrogen
1 react in the hot engine / at high temperature 1
(d) any three from: ignore references to melting point
3
• ethanol needs a higher temperature to burn than petrol or ethanol has a higher flashpoint than petrol
• ethanol releases less energy (per litre) than petrol
• sugar is renewable or crude oil is non-renewable / will run out
• sugar cane growth is unreliable / slow or crude oil is a reliable supply allow ethanol is not readily available or petrol is readily available
• ethanol is made by a batch / slow process or petrol is made by a continuous
/ fast process
• ethanol is carbon neutral or petrol contains ‘locked up’ carbon dioxide
• sugar / sugar cane should be used for food not for fuels accept idea of food shortages a justified conclusion that adds value accept one additional point from the list above as long as one comparison of replacing petrol with ethanol is made
1
[12]