Fuels

Question 1

What is a fuel?

Answer 1

Fuels are chemicals which give out energy when they burn.

Question 2

What gets used up in the air when fuels combust?

Answer 2

The combustion of fuels uses up oxygen from the air.

Question 3

What is a reaction that gives off heat?

Answer 3

Reactions that give out heat are called exothermic reactions.

Question 4

Fossil fuels?

Answer 4

Fossil fuels are a finite resource and cannot be replaced.

Question 5

What are the three main fossil fuels?

Answer 5

Our three main fossil fuels are coal, oil and natural gas.

Question 6

How are different substances in a mixture separated?

Answer 6

Because different substances in a mixture have different boiling points they can be separated by fractional distillation into groups of molecules with a certain boiling range.

Question 7

What does flammable mean?

Answer 7

The warning label “flammable” appears as on many (organic) chemical bottles, to warn of the risk if taken near a flame.

Question 8

What does viscosity mean?

Answer 8

The larger the molecule the higher the viscosity is of a liquid, i.e the thicker it is.

Question 9

What does a larger molecule of a hydrocarbon mean?

Answer 9

The larger the hydrocarbon molecules the more energy will be required to evaporate the substance. Hydrocarbons with larger molecules are less flammable.

Question 10

What is a hydrocarbon?

Answer 10

Hydrocarbons are compounds that contain only carbon and hydrogen atoms.

Question 11

What is the test for carbon dioxide?

Answer 11

The test for carbon dioxide is that it turns lime water milky/cloudy.

Question 12

What is the test for water?

Answer 12

The test for water is that it turns cobalt chloride paper from blue to pink.

Question 13

What happens when hydrocarbons burn?

Answer 13

When hydrocarbons burn they produce only carbon dioxide and water.

Question 14

What if a hydrocarbon has its air supply restricted while burning.

Answer 14

If a hydrocarbon has its air supply restricted, while it is burning it may produce C (soot) and CO (a poisonous gas) as well as CO2 and H2O.

Question 14

Why are longer chains of molecules harder to break down?

Answer 14

Longer chains of molecules are harder to break down because the intermolecular forces increase as chain length increases, also longer chains become tangled so need to be boiled at a higher temperature to be broken down.

Question 15

If a substance has a higher boiling point why would it be less flammable?

Answer 15

If a substance has has a higher boiling point then they are harder to evaporate then there will be less vapours and therefore less flammable.

Question 16

What is a biofuel?

Answer 16

A biofuel is a fuel made from living matter, bio fuels are also renewable.

Question 17

What is a catalytic converter?

Answer 17

A catalytic converter is a device found in a car exhaust which can be used to change (convert) harmful pollutant gases into less harmful ones using a catalyst.

Question 18

Carbon monoxide?

Answer 18

Carbon monoxide’s main source is from incomplete combustion, it is a poisonous gas and it can be prevented by having an adequate supply of oxygen.

Question 19

Sulfur dioxide?

Answer 19

Sulfur dioxide’s main source is from the burning of fossil fuels, it contributes to the problem of acid rain and it can be prevented by a process called ‘scrubbing’

Question 20

Unburnt petrol?

Answer 20

Unburnt petrol’s main source is from a car engine, it is toxic and it can be prevented by having an adequate supply of oxygen.

Question 21

Nitrogen oxides?

Answer 21

Nitrogen oxide’s main source is from a car engine, it can cause acid rain and breathing problems and it can be prevented by a catalytic converter.