C4: Air and Water
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% of Nitrogen in the air
78%
% of Oxygen in the air
21%
% of Argon in the air
0.9%
% of Carbon Dioxide in the air
0.04%
Nitrogen Boiling Point
-196 C
Argon Boiling Point
-186 C
Oxygen Boiling Point
-183 C
How are the gases in the air separated in industry?
Fractional Distillation of Liquid Air
Fractional Distillation of the Air Process
• Compress the air to 150 times atmospheric pressure. This warms up the air, so it is then passes over cold water pipes) • Pressure is released, and air is allowed to expand rapidly. Causes temp to drop enough that the gases -> liquids. CO2 and H2O are removed easily as they are solid at this temperature. • Temp is slowly increased and the gases boil off one by one. Nitrogen - Argon - Oxygen
O I L R I G
Oxidisation is loss (of electrons) Reduction is gain (of electrons)
Bases
The oxide, hydroxide or carbonate of a metal that will react with an acid, forming a salt as one of the products. Bases dissolved in water are alkalis.
Amphoteric Metals
An oxide that displays both acidic and basic properties.
Test for oxygen gases.
A glowing splint will relight in oxygen.
Metal oxides are…
Basic
Non-Metal oxides are…
Acidic
3 elements of a water filter and their purposes.
> Carbon- Reduces chlorine in water Ion-exchange resin- removes calcium, magnesium, lead, copper and aluminium. Silve- Discourages the growth of bacteria in the filter.
Desalination
The removal of salts from water to make it safe to drink.
Positives of Fluoridation of Water.
> Reduces cavities. Protects those with bad dental hygiene. Protects from bacteria that causes heart disease.
Negatives of Fluoridation of Water.
> Fluorosis- Weakens bones. Benefit for teeth is not significant. Ethically wrong- no consent from people. Can cause learning difficulties and Alzheimers Can’t control intake.
Which metal rusts?
Iron
What is needed for iron to rust?
Oxygen and Water.
What prevents rusting?
> Paint > Oil/ Grease > Plastic > Less reactive metal > More reactive metal
Galvanised
Iron or Steel objects that have been protected from rusting by a thin layer of zinc metal at their surface.
Sacrificial Protection
An effective way to prevent rusting whereby a metal more reactive than iron (e.g zinc or magnesium) is attached to or coated on an object.