Crude Oil
6 marks · NormalThe properties and uses of fuels produced from crude oil can affect both technology and human health.
Explain why incomplete combustion of fuels can be more harmful to health than complete combustion.
Suggest one reason why gasoline is preferred over diesel or kerosene as a fuel for most cars.
Apart from car fuel, state one other use of the gasoline fraction.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Incomplete combustion produces carbon monoxide, which is poisonous. Carbon monoxide binds to haemoglobin, stopping blood from carrying oxygen, and can cause illness or death. · must show incomplete combustion forms CO, CO is poisonous, prevents oxygen transport in blood
(b) Gasoline burns more cleanly/quicker; it is more volatile so starts engines easily compared to diesel or kerosene. · must show burns more cleanly, more volatile/easier engine starting
(c) Used as a solvent, or in the production of chemicals. · must show solvent use, chemical production
Common mistakes: Not stating why CO is dangerous; Confusing why diesel/kerosene are less preferred; Giving non-petrol use
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · States that incomplete combustion forms carbon monoxide.
M2 (a) · 1 mark · States that carbon monoxide is poisonous/toxic to humans.
A1 (a) · 1 mark · Explains that carbon monoxide prevents blood from carrying oxygen.
B1 (b) · 1 mark · Gives one valid reason for gasoline preference: burns more cleanly, is more volatile.
B2 (b) · 1 mark · Explains that gasoline enables easier starting or smoother running of engines.
C1 (c) · 1 mark · Gives another correct use of gasoline fraction (e.g., solvent, making chemicals).
Worked solution
a) Incomplete combustion forms carbon monoxide, which is a toxic gas. Carbon monoxide binds to haemoglobin in blood, preventing it from transporting oxygen. This can cause health issues or death.
b) Gasoline is preferred because it burns more cleanly and is more volatile, allowing cars to start more easily and engines to run smoothly.
c) Gasoline can also be used as a solvent or in making other chemicals.