What is air?
Air is a mixture of gases mainly nitrogen and oxygen, with small amounts of carbon(IV) oxide, noble gases and water vapour.
What percentage of air is nitrogen?
About 4/5 (approximately 78%) of air.
What percentage of air is oxygen?
About 1/5 (approximately 21%) of air.
How can components of air be separated?
By physical means.
How does water vapour enter the atmosphere?
Through evaporation from oceans, rivers, lakes, seas and reservoirs.
Which is the most abundant noble gas in air?
Argon.
How can carbon(IV) oxide in air be detected?
By passing air through limewater or potassium hydroxide solution.
What maintains the balance of carbon(IV) oxide in the atmosphere?
Respiration and photosynthesis.
Which is the most reactive component of air?
Oxygen.
State two processes oxygen is involved in.
Combustion and respiration (also corrosion).
What is corrosion?
The deterioration of metals when exposed to air over time.
What is rusting?
The corrosion of iron.
State one method of preventing rusting.
Painting, greasing, or coating with another metal like chromium.
What is air pollution?
The release of harmful substances into the atmosphere in significant quantities.
State one cause of air pollution.
Burning of fossil fuels such as coal and gasoline.
What is particulate matter?
Tiny solid particles like dust, smoke, soot and heavy metals suspended in air.
What is carbon(II) oxide produced from?
Incomplete burning of fossil fuels.
Why is carbon(II) oxide dangerous?
It binds with haemoglobin and prevents oxygen transport in the body.
What causes the greenhouse effect?
Carbon(IV) oxide trapping heat in the atmosphere.
What causes acid rain?
Oxides of sulphur and nitrogen reacting in the atmosphere.
What effect does sulphur(IV) oxide have?
It causes respiratory problems and contributes to acid rain.
What is the effect of CFCs?
They destroy the ozone layer.
What is a flame?
The region where gases react chemically, producing heat and light.
Name the two main types of flames.
Luminous and non-luminous flames.
How does hydrogen burn?
With a faint, non-luminous flame.
How many zones does a candle flame have?
Four zones.
Which zone of a candle flame is luminous?
The bright yellow zone where incomplete combustion occurs.
What happens when the air hole of a Bunsen burner is closed?
A luminous yellow flame is produced.
What happens when the air hole of a Bunsen burner is open?
A hotter, non-luminous blue flame is produced.
Why is the non-luminous Bunsen flame preferred in laboratories?
It is hotter, cleaner and produces complete combustion.
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