C1.23a Using the fractions Name
Class
Date
The fractions listed in the box can be obtained from crude oil. Each fraction has different uses.
● ● ● ● ● ● 1
2
bitumen diesel oil fuel oil gases kerosene petrol
Which fraction (or fractions): a
can be used for making roads
b
is the most viscous
c
is used in jet engines
d
has the smallest number of carbon atoms in the molecules
e
is used as fuel for engines in motorbikes and most cars
f
is used as fuel for engines in lorries and trains
g
can be used for making flat roofs
h
is used for heating homes?
Why is crude oil separated into different fractions? ________________________________________________________________________________
3
The paragraph below shows a student's summary of the lesson, but it contains mistakes. Underline the parts that are wrong, and write a correct version of them. Crude oil is a mixture of different hydrocarbon elements. It is mixed into different fractions in a refinery. This happens by fractional evaporation. Each fraction is a pure liquid. Kerosene is used for ship engines, and fuel oil is used in cars. Petrol is used in cars and diesel is used in camping stoves.
© Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.
C1.23b Diesel or petrol? You do not need to remember the details on this sheet for your exam, but you could be asked to apply your knowledge to unfamiliar situations. Most lorries and farm vehicles use diesel as a fuel, but most cars use petrol. Why the difference? Both types of engine burn the fuel in compressed air. The heat released by burning makes the air and waste gases expand, which pushes on a piston to turn the engine. In a petrol engine, the fuel–air mixture is ignited using a spark. The petrol is mixed with the air before going into the engine, or the fuel is injected into the cylinder just before the spark. The more the air is compressed before the fuel–air mixture explodes, the less of the energy in the petrol is wasted. However, the compression cannot go above a certain amount or the fuel–air mixture would explode before it is meant to and damage the engine. Diesel engines work slightly differently – there are no spark plugs. Instead, the air in the engine is compressed to higher pressures than in a petrol engine. Compressing a gas heats it up, and by the time the diesel fuel is injected into the compressed air, the air is hot enough to ignite the diesel. A diesel engine gives more miles per litre of fuel than a petrol engine of similar power and the engine usually lasts longer. But it is bigger, heavier, noisier and more expensive to buy than the equivalent petrol engine. The table shows a comparison between two cars – they are the same model, the only difference is the engine. Carbon dioxide emissions (g/km)
0–60 mph (sec)
Cost of car
1.2 petrol
140
15.1
1.4 diesel
127
15.4
Engine
Kilometres per litre of fuel In town
Out of town
Combined
£9865
12.8
20.4
17.0
£10830
16.7
23.8
20.9
1
Describe some similarities between diesel fuel and petrol.
2
How are diesel and petrol different in terms of: a the number of carbon atoms in their molecules b ease of ignition c boiling point?
3
a What are the similarities between a petrol and a diesel engine? b What are the differences?
4
a Suggest some advantages of owning a car with a diesel engine compared to one with a petrol engine. b What are the disadvantages?
5
Why might someone decide to buy a car with a petrol engine instead of the same model with a diesel engine? Suggest as many reasons as you can.
6
Suggest why virtually all lorries have diesel engines.
© Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.
Sheet 1 of 2
C1.23b Diesel or petrol? (cont.) 7
Mr Smith drives about 15 000 kilometres per year. Use the combined figures from the table above, and assume that the price of fuel (petrol and diesel) is ÂŁ1 per litre. a If he buys a petrol-engined car, how many litres of petrol will he buy in a year? b How many litres of diesel would he buy if he had a diesel car? c How much money would he save in fuel costs in one year with a diesel car? d How long will it take him to save the extra money he spent buying a diesel car?
Extra challenge 8
Explain how your answer to question 7 would change if: a the price of diesel is a few pence per litre dearer than petrol b the price of all fuels increases c Mr Smith drives mostly in town (urban) d Mr Smith drives 50 000 km per year, mostly on motorways (out of town driving).
Š Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.
Sheet 2 of 2