Questions on Energy Sources
Q6. The table below gives information about three fuels that can be used in cars. 
shows a substance is produced when the fuel burns. X shows a substance is not produced when the fuel burns.
fuel |
physical state |
energy released, in kJ/kg |
some of the substances produced when the fuel burns |
carbon monoxide |
sulphur dioxide |
water |
petrol |
liquid |
48 000 |
|
|
|
hydrogen |
gas |
121 000 |
X |
X |
|
ethanol (alcohol) |
liquid |
30 000 |
|
X |
|
(a) Which fuel, in the table, releases the least energy per kilogram (kg)?
ethanol (or alcohol)
1 mark
(b) Some scientists say that if hydrogen is burned as a fuel there will be less pollution. From the information in the table, give one reason why there will be less pollution.
Burning petrol produces carbon monoxide and suphur dioxide (polutant gases) and ethanol produces carbon monoxide but burning hydrogen does not produce sulphur dioxide or carbon monoxide. It is therefore not producing as much pollution.
1 mark
(c) Which of the three fuels in the table can be compressed into a small container?
Hydrogen 
1 mark
(d) Which gas in the air is needed for fuels to burn?
Oxygen
1 mark
(e) Petrol and ethanol are both fuels. Petrol is made from oil. Scientists say that oil could run out in 100 years. In some countries people plant sugar cane and use it to make ethanol. Sugar cane will not run out. Explain why.
Sugar cane can be grown in a short period of time. Seeds from the mature plants can be collected and then planted to grow a new crop after it has been harvested for fuel. It is therefore a renewable resource. It is a form of biomass.
1 mark
Maximum 5 marks
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