Crude oil and fuels

Question 1

What is a hydrocarbon?

Answer 1

A molecule that only contains carbon and hydrogen

Question 2

What is crude oil?

Answer 2

• Hydrogen and carbon
• Compound mixture- not chemically combined
• Family- alkanes

Question 3

What is the formula of an alkane?

Answer 3

C n H 2n+2

Question 4

What is the formula of an alkene?

Answer 4

C n H 2n

Question 5

What happens in the combustion of a hydrocarbon?

Answer 5

Hydrocarbon + oxygen –> carbon dioxide + water

Question 6

How can we separate crude oil?

Answer 6

Fractional distillation

Question 7

How does fractional distillation work (in separating crude oil)?

Answer 7

• Heat the mixture of hydrocarbons (in a furnace) which boil off at different temperatures
• Can then collect them in fractions as they condense and each is useful for different purposes

Question 8

What are the properties of long chain hydrocarbons? (compared to short chain)

• Boiling point
• Volatility (how easily it turns into a gas)
• Viscosity (how easily it flows)
• Flammability (how easily it burns)

Answer 8

• High boiling point
• Doesn’t have a tendency
• Thick (high/viscous)
• Less flammable (smoky flame)

Question 9

What are the properties of short chain hydrocarbons?
(compared to long chain)
- Boiling point
- Volatility (how easily it turns into a gas)
- Viscosity (how easily it flows)
- Flammability (how easily it burns)

Answer 9

• Low boiling point
• Does have a tendency
• Very runny (low)
• More flammable

Question 10

Why are the properties of long and short chain hydrocarbons different?

Answer 10

• The more atoms there are, the more stable they are (takes more time/energy for bonds to be broken on long chains)
• Higher molecular mass makes things thicker
• As molecular mass increases so does boiling point as it takes more energy for bonds to be broken

Question 11

How is pollution caused?

Answer 11

In the burning of fossil fuels

Question 12

What product is formed from the combustion of the impurity sulfur and what problems does it cause?

Answer 12

• Sulfur dioxide

- Poisonous, causes acid rain

Question 13

What product is formed in the combustion of the impurity nitrogen and what problems does it cause?

Answer 13

• Nitrogen oxide

- Poisonous, causes acid rain

Question 14

What product is formed from other particles in the combustion of fossil fuels and what problems do they cause?

Answer 14

• Unburnt particles

- Cancer, causes smog

Question 15

What global warming? What are the causes?

Answer 15

Warming of the earth due to greenhouse gases in the atmosphere trapping infra-red radiation from the surface (also caused hole in ozone layer)

Question 16

What is a greenhouse and when are they released?

Answer 16

Gases such as carbon dioxide in the atmosphere that absorb infra-red radiation from the earth’s surface
Released when we burn any fuel

Question 17

What is global dimming? What are the causes?

Answer 17

A gradual reduction in the amount of light reaching the earth’s surface
Particulates (tiny particles made of unburnt hydrocarbons) travel to the upper atmosphere, reflecting sunlight and water vapour back into space

Question 18

What is acid rain? What are the causes?

Answer 18

Rain that is acidic due to dissolved gases, such as sulfur dioxide, produced by the burning of fossil fuels

Question 19

What are the solutions for lowering pollution levels?

Answer 19

• Reduce fuel use
• Ban CFCs (chloro flouro carbons)- harmful to ozone layer
• Use renewable fuels
• Catalytic converters: transition metals filter which causes carbon monoxide and nitrogen oxide in exhausts to react and become less harmful

Question 20

What is the reaction in a catalytic converter which causes less harmful substances to be made?

Answer 20

Carbon monoxide + nitrogen oxide –> carbon dioxide + nitrogen

Question 21

What is biodiesel?

Answer 21

A fuel made from plants (fresh or recycled vegetable oil)

Question 22

What are the advantages of biodiesel?

Answer 22

• Cheap to make
• Anyone can make it
• Non-toxic (no noxious fumes given off)
• Biodegrades
• Clean- produces less pollution than diesel and is pretty carbon neutral, absorbing nearly as much carbon dioxide as it burns
• Can be made from “scraps”- used vegetable oil
• Only by-product is glycerin which can be used to make soap
• Doesn’t exploit people and the environment like oil industries do

Question 23

What are the disadvantages of biodiesel?

Answer 23

• You must be prepared with equipment
• Hard to produce in large batches
• Must be an engine that would use diesel
• Still releases carbon dioxide in emissions

Question 24

Give three examples of groups of hydrocarbons which come out of different fractions

Answer 24

(in degrees celsius) (from bottom up)

• Bitumen
• 340 Oil
• 250 Diesel
• 180 Kerosene (jet fuel)
• 110 Naphtha
• 40 Petrol
• Refinery gas (bottled gas)