Air and water

Question 1

What are the main components of dry air?

Answer 1

• Nitrogen (78.1%)
• Oxygen (20.9%)
• Argon (0.9%)
• Carbon dioxide (0.04%)

Question 2

How are the different gases in the air separated for industrial use?

Answer 2

FRACTIONAL DISTILLATION:
-First the air has to be cold enough for all of it to condense into a liquid- It has to be cooled to a temperature below 200 °C and compressed to 150 times atmospheric pressure
-The carbon dioxide and water are filtered out of the mixture (usually before the final cooling) as they are solids at this low temperature
-The liquid is then warmed and the remaining components eventually biol off in the order:
Nitrogen, argon and then oxygen

Question 3

What effect do CO2 and CH4 have on the earth

Answer 3

• CO2 and CH4, are able to absorb infrared radiation
• Some of the energy radiated from the Earth is trapped in the atmosphere
• Temperature rises
• The higher the proportion of greenhouse gases in the atmosphere, the more energy is absorbed

Question 4

What factors have led to the production of CO2 and CH4?

Answer 4

CO2:

• Burning fossil fuels
• Deforestation

CH4:

• Cattle farming
• Rice fields
• Landfill sites

Question 5

What are the 3 main pollutants on earth

Answer 5

• Carbon monoxide CO
• Carbon dioxide CO2
• Sulfur dioxide SO2
• Oxides of nitrogen NOx

Question 6

What are the origins and effects of carbon monoxide?

Answer 6

ORIGINS:

• It is formed by the incomplete combustion of fossil fuels
• Gas fires in heating
• Gas boilers used for heating (water/ central heating)
• Engines in cars and other vehicles

EFFECTS:

• Binds more strongly to haemoglobin than oxygen- greatly reduces O2 n the blood
• Exposure can lead to headaches/ drowsiness/ even death

Question 7

What are the origins and effects of carbon dioxide?

Answer 7

ORIGINS:

• Respiration
• Decay of dead plants or animals
• Dissolved CO2 escaping from the sea water
• Complete combustion of fossil fuels

EFFECTS:
- its increase in the atmosphere is contributing further to the greenhouse effect, leading to global warming and climate change

Question 8

What are the origins and effects of sulfur dioxide?

Answer 8

ORIGINS:

• Most fuels contain small amounts of sulfur containing compounds as impurity. The sulfur present in them is oxidised to give sulfur dioxide (SO2)
• It reacts with water and oxygen in the atmosphere to produce sulfuric acid, one of the components of ‘acid rain’

EFFECTS:

• Sulfur dioxide is a poisonous, colourless, acidic gas with a choking smell
• Sulfur dioxide is a poisonous, colourless, acidic gas with a choking smell
• The sulfuric acid in acid rain erodes stonework, increases metal corrosion, increases the leaching of soil (removal of important minerals) and is also harmful to animal and plant life

Question 9

What are the origins and effects of the oxides of nitrogen?

Answer 9

ORIGINS:
-When combustion occurs, at the high temperatures and pressures generated, it is possible for the nitrogen in the air to react with the oxygen to give a number of different oxides of nitrogen

EFFECTS:

• They react with oxygen and water in the atmosphere to generate nitric acid, another component of ‘acid rain’
• They are also toxic gases and can trigger asthma attacks

Question 10

What is the role of chlorine and fluoride ions in drinking water?

Answer 10

Chlorine (Cl2):
-To sterilise the water as it kills harmful bacteria.

Fluoride ions (F−):
-Fluoride ions (for example, in sodium fluoride) helps protect against tooth decay