Unit 1: 4 - Crude Oils and Fuels

Question 1

How can we separate a mixture of liquids?

Answer 1

By distillation.

Question 2

What are most of the compounds in crude oil?

Answer 2

Hydrocarbons.

Question 3

What is an alkane?

Answer 3

A saturated hydrocarbon.

Question 4

What is the general formula for alkanes?

Answer 4

C₂H_2n+2

Question 5

How do we seperate a mixture of hydrocarbons in crude oil?

Answer 5

By fractional distillation.

Question 6

Where is the crude oil vaporised for fractional distillation?

Answer 6

A fractionating column.

Question 7

What are the fractions that boil at around 20-50° used for (and come out of the top)?

Answer 7

Refinery and petroleum gas.

Question 8

What is the second highest boiling point hydrocarbons used for?

Answer 8

Gasoline/Petrol (for use in car engines).

Question 9

What are the fractions that leave in the middle?

Answer 9

Kerosene (aircraft fuel).

Question 10

What are the second-to-bottom fractions used for?

Answer 10

Diesel oil/gas oil (for use in diesel engines and as boiler fuel).

Question 11

What is the residue from fractional distillation used for?

Answer 11

Making roads and flat roofs.

Question 12

Fractions with low boiling ranges have low _____ and produce less _____, as well as burn easily because they are _____

Answer 12

Low viscocity and produce less smoke, they are flammable (and burn with a clean flame).

Question 13

When pure hydrocarbons burn completey they are _____ to CO₂ and H₂O.

Answer 13

Oxidised

Question 14

What are the 2 problems with the fuels that we burn?

Answer 14

• They sometimes do not get burned completely;
• They contain other substances, such as sulfur.

Question 15

Why does incomplete combustion produce carbon monoxide?

Answer 15

Because there is a limited supply of oxygen for the carbon to bond with.

Question 16

What are particulates and why are they produced?

Answer 16

Solid particles of carbon (soot) that are released during incomplete combustion where there is not enough oxygen to react the carbon with.

Question 17

What do particulates contribute towards?

Answer 17

Global dimming.

Question 18

What is the problem with burning fuels containing sulfur?

Answer 18

It produces sulfur dioxide, which causes acid rain.

Question 19

What is produced at the high temperatures required to burn fuels and what does this cause?

Answer 19

Nitrous oxides are made when the nitrogen and the oxygen in the air reacts with eachother. This causes acid rain and can cause asthma.

Question 20

What is carbon dioxide and what does it cause?

Answer 20

It is a greenhouse gas and contributes towards global warming.

Question 21

Why do various compounds released while burning fuels produce acid rain?

Answer 21

They dissolve in rain droplets to make an acidic solution.

Question 22

What are exhaust systems in cars fitted with to remove carbon monoxide and nitrous oxides?

Answer 22

Catalytic converters.

Question 23

How are particulates removed from waste gases?

Answer 23

Using filters.

Question 24

How do we help prevent sulfur dioxide emmissions?

Answer 24

By removing sulfur dioxide from fuels (sulfur-reduced fuels).

Question 25

What are biofuels made of?

Answer 25

Plant or animal products (they are renewable).

Question 26

What is biodiesel made up of?

Answer 26

Vegetable oils extracted from plants.

Question 27

Give the main advantage of biodeisel.

Answer 27

It makes little contribution to carbon dioxide levels; the CO₂ given up when it burns was taken from the atmosphere when it grows.

Question 28

Give the main disadvantage of biodeisel.

Answer 28

Plants grown use large areas of farmland which could be used for food.

Question 29

Give an example of a biofuel (apart from biodeisel). Explain where it comes from and how it is distrobuted and used.

Answer 29

Ethanol. It is obtained by fermenting sugar cane/sugar beet. It is a liquid so can be stored and distrobuted like other fuels. It is mixed with petrol and used in engines.