Air Pollutants

Question 1

Combustion

Answer 1

A rapid reaction between a substance and oxygen that releases heat and light energy. When a substance burns, it is said to combust

Question 2

Complete Combustion

Answer 2

This is when there is enough oxygen available for all of the carbon atoms in a fuel to burn and form carbon dioxide.

Question 3

Word Equation

Answer 3

The word equation for the complete combustion of a hydrocarbon fuel is:

Hydrocarbon + Oxygen > Carbon dioxide + Water

Question 4

Incomplete combustion

Answer 4

If there is a shortage of oxygen when a hydrocarbon fuel is burned, incomplete combustion takes place.

Question 5

Word Equation 2

Answer 5

Instead of producing carbon dioxide and water, carbon monoxide and water is produced

Hydrocarbon + Oxygen > Carbon monoxide + Water

Question 6

Air Pollution

Answer 6

This is the presence of substances in the air (pollutants). These are usually caused by human activities and are harmful to health or the environment

Question 7

Air Components

Answer 7

Air is made up of a mixture of gases - about 78% nitrogen, 21% oxygen and 1% other gases including carbon dioxide

Question 8

Fuels & The Environment

Answer 8

Most fuels contain hydrogen and carbon, but many also contain sulphur. When fuel burns, many substances are released: carbon dioxide, water vapour, carbon monoxide, sulphur dioxide, oxides of nitrogen and particulates

Question 9

Carbon dioxide in nature

Answer 9

Carbon dioxide is an important atmospheric gas as it prevents heat radiation produced by the Earth from escaping into space - the greenhouse effect. Without carbon dioxide the Earth would not be warm enough for life

Question 10

Carbon dioxide from fuels

Answer 10

CO2 is produced during the complete combustion of hydrocarbon fuels, such as crude oils or natural gas. Increased CO2 levels is causing drastic changes to the climate, known as global warming

Question 11

Nitrogen oxides

Answer 11

As hydrocarbons burn in internal combustion engines, high temperatures are created. At these temperatures, nitrogen in the air, which is normally unreactive, combines with oxygen to form nitrogen monoxide (NO)

Question 12

Carbon monoxide

Answer 12

Carbon monoxide (CO) is a colourless odourless and very toxic gas that reduces the ability of the blood to carry oxygen. Carbon monoxide poisoning kills 7 people a year in the UK

Question 13

Soot

Answer 13

When the amount of oxygen available is very limited, incomplete combustion can also produce carbon particulates, often referred to as soot

Question 14

Particulates

Answer 14

Carbon particles are produced in the combustion of long chain hydrocarbons, such as wax in candles. The carbon particles glow in heat and give it a yellow colour

Question 15

Sulphur dioxide

Answer 15

Sulphur is found naturally in all fossil fuels. When a hydrocarbon fuel containing sulphur impurities is burned, the sulphur reacts with oxygen and sulphur dioxide is produced. It then dissolves in rain water to produce acid rain.

Question 16

Decreasing Sulphur Dioxide

Answer 16

Many fuels contain sulfur which is released as sulfur dioxide into the atmosphere. This results in acid rain. To reduce sulphur emissions we can remove sulphur from natural gas and fuels (expensive and increases fuel prices), use gas scrubbers (alkaline that neutralises sulphur dioxide), etc.