Crude oil

Question 1

What are the main fractions obtained from crude oil?

Answer 1

The main fractions obtained from crude oil are liquified petroleum gas, petrol, kerosene, diesel, fuel oil and bitumen.

Question 2

What is the use of liquified petroleum gas (LPG) obtained from crude oil?

Answer 2

LPG is used for domestic heating and cooking.

Question 3

What is the use of petrol (gasoline) obtained from crude oil?

Answer 3

Petrol is used as fuel for cars.

Question 4

What is the use of kerosene obtained from crude oil?

Answer 4

Kerosene is used as jet fuel (paraffin).

Question 5

What is the use of diesel obtained from crude oil?

Answer 5

Diesel is used for diesel engines (gas oil).

Question 6

What is the use of heavy fuel oil obtained from crude oil?

Answer 6

Heavy fuel oil is used for ships and power stations

Question 7

What is the use of bitumen obtained from crude oil?

Answer 7

Bitumen is used for surfacing roads

Question 8

What is a fuel?

Answer 8

A fuel is a substance that, when burned, releases heat energy.

Question 9

What are the products of complete combustion of hydrocarbons?

Answer 9

carbon dioxide and water.

Question 10

What are the products of incomplete combustion of hydrocarbons?

Answer 10

carbon monoxide, soot, and water.

Question 11

Why is carbon monoxide poisonous?

Answer 11

reduces the capacity of blood to carry oxygen.

Question 12

What happens in car engines that leads to the formation of nitrogen oxides?

Answer 12

High temperatures in car engines allow nitrogen and oxygen from the air to react, forming nitrogen oxides.

Question 13

How does the combustion of impurities in hydrocarbon fuels lead to the formation of sulfur dioxide?

Answer 13

When fossil fuels are burned, sulfur impurities are oxidized to produce sulfur dioxide.

Question 14

How do sulfur dioxide and oxides of nitrogen contribute to acid rain?

Answer 14

Sulfur dioxide and oxides of nitrogen can react with water in the atmosphere to produce acid rain.

Question 15

How are long-chained alkanes as well as short-chained alkanes converted to alkenes?

Answer 15

Long-chain alkanes are converted by catalytic cracking at a high temperature using silica or alumina as the catalyst.

Question 16

Why is cracking necessary?

Answer 16

it allows for the production of smaller, more useful products from larger, less valuable ones

Question 17

Describe how compound D can be obtained from crude oil using the industrial process of fractional distillation. (4)

Answer 17

• The crude oil is heated and vaporized
• Vapour enters into the bottom part of the fractionating column
• There is a temperature gradient in the column
• Different hydrocarbons have different boiling points and compound D can be collected from the top part of the column as refinery gas.

Question 18

Describe how the boiling point, colour, and viscosity of the fuel oil fraction differ from those of the gasoline fraction

Answer 18

Fuel oil fraction has a higher boiling point, darker color, and higher viscosity.

Question 19

State the condition that causes incomplete combustion

Answer 19

lack of air

Question 20

Explain why cracking is an important process in the oil industry

Answer 20

• Produces smaller molecules
• Smaller molecules have greater demand
• Smaller molecules are used to make petrol
• Cracking produces alkenes which are to make plastics

Question 21

Explain why it is important to crack long-chain hydrocarbon fractions.

Answer 21

• Smaller molecules are in greater demand
• Greater supply of long-chain hydrocarbons

Question 22

The petrol fraction is obtained from near the top of the column.

The bitumen fraction is obtained from the bottom of the column.

Explain how the petrol and bitumen fractions differ in their properties and uses. (6)

Answer 22

• petrol has shorter (carbon) chains
• petrol has a lower melting point/boiling point
• petrol has a lower viscosity
• petrol ignites/burns more easily
• bitumen does not combust completely (due to the high number of carbon atoms per molecule)
• burning bitumen produces lots of carbon monoxide/soot

Uses of petrol fraction:

• fuels in cars/motorbikes/transport

Uses of bitumen fraction:

• used for road surfaces