1.4 Crude Oil and Fuels

Question 1

What is crude oil and how is it formed?

Answer 1

A mixture of large compounds (mainly hydrocarbons) formed from the buried remains of plants and animals

Question 2

What is a mixture?

Answer 2

Two or more elements that aren’t chemically bonded to each other

Question 3

What properties depend on the size of the hydrocarbon?

Answer 3

The shorter the molecule:

• Less viscous (more runny)
• More volatile (lower boiling point)
• More flammable

Question 4

What is the formula for an alkane?

Answer 4

C_nH_2n+2

Question 5

Do alkanes have a double bond?

Answer 5

No

Question 6

What is used to split seperate groups of hydrocarbons?

Answer 6

Fractional distillation

Question 7

Explain fractional distillation

Answer 7

A fractionating column is very hot at the bottom and cooler at the top. Vaporised crude oil rises up the column, the different molecules condense at their specific condensing temperature.

Question 8

What do most fuels contain?

Answer 8

Carbon and hydrogen

Question 9

What happens during combustion of a fuel?

Answer 9

Carbon and hydrogen are oxidised to make CO₂, water vapour and energy

Question 10

If a fuel contains sulfur impurites, what gas is released?

Answer 10

Sulfur dioxide

Question 11

What is released if a fuel is partially combusted?

Answer 11

Particulates of soot and carbon monoxide

Question 12

What does sulfur dioxide cause and how?

Answer 12

Acid rain. Sulfur dioxide mixes with clouds to for sulfuric acid, then it rains

Question 13

What are the problems with acid rain?

Answer 13

• Lakes become acidic, plants and animals die as a result
• Kills trees
• Damages limestone buildings and statues

Question 14

What does carbon dioxide cause?

Answer 14

Climate change

Question 15

What do particulates cause?

Answer 15

Global dimming

Question 16

How can sulfur emissions be reduced?

Answer 16

• Sulfur can be removed from fuels before they’re burnt
• Sulfure dioxide can be removed from waste gases after combustion
• Use less fossil fuels

Question 17

What renewable alternative fuels are being developed? (3)

Answer 17

• Biofuel
• Biodiesel
• Hydrogen gas

Question 18

What are the advantages/disadvantages of biofuel?

Answer 18

Advantages:

• Carbon neutral
• The only product is water

Disadvantages:

• Engines will need to be converted before they’ll work with biofuel.
• Not widely available
• Farmers will grow crops to make ethanol over food, this will increase food prices

Question 19

What are the advantages/disadvantages of biodiesel?

Answer 19

Advantages:

• Carbon neutral
• Engines don’t need to be converted
• Produces much less sulfur dioxide and particulates

Disadvantages:

• We can’t make enough to completely replace diesel
• Expensive
• Farmers will grow crops to make biodiesel over food, this will increase food prices

Question 20

What are the advantages/disadvantages of hydrogen gas?

Answer 20

Advantages:

• Combines with oxygen to form just water so it’s very clean

Disadvantages:

• A special, expensive engine is needed
• Hydrogen isn’t widely available
• Energy is needed to make hydrogen
• Hydrogen is hard to store