78% nitrogen, 21% oxygen and small amounts of argon, carbon dioxide, methane and water vapour.
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How can we get the products from dry air?
Through fractional distillation of air.
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How can air be fractionally distilled?
1) Air filtered to remove dust. 2) Cooled to -200; becomes liquid. 3) During cooling water vapour condenses; removed. 4) CO2 freezes; removed. 5) liquid air enters column; heated slowly. 6) remaining gases separated by FD. O2 and argon together.
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How can you test for oxygen?
With a glowing splint. If the splint is placed in the test tube and relights, it contains oxygen.
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What is an oxidation reaction?
When oxygen is being added.
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What is a reduction reaction?
When oxygen is being removed.
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Do metal oxides give acidic or alkaline solutions?
Alkaline solutions
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Do non-metal oxides give acidic or alkaline solutions?
Acidic solutions
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What colour flame does magnesium burn?
Bright white flame.
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Is magnesium oxide dissolved in water acidic or alkaline?
slightly alkaline
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What colour flame does carbon burn?
Orangey/yellowy flame
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Is carbon dioxide dissolved in water acidic or alkaline?
Slightly acidic
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What colour flame does sulfur burn?
Pale blue flame
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Is sulfur dioxide dissolved in water acidic or alkaline?
acidic
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What colour flame does sodium burn?
bright yellow flame
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Is sodium oxide dissolved in water acidic or alkaline?
alkaline
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What colour flame does iron burn?
orange flame.
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Can iron oxide dissolve in water?
No
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What colour powder is formed when iron burns?
A black powder called iron oxide.
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What pollutants could be released by burning a fuel? (3)
Carbon monoxide, nitrogen oxide, sulfur dioxide.
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When is carbon monoxide formed?
Formed when hydrocarbon fuels (e.g petrol or diesel) are burnt without enough oxygen, this is partial or incomplete combustion.
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Why is carbon monoxide poisinus?
It can stop blood cells doing their job properly of carrying oxygen around the body. It combines with the haemoglobin in the blood cells, meaning the blood cells can carry less oxygen.
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What can a lack of oxygen in the blood cause?
Fainting, coma or even death.
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When does the sulfur dioxide in fossil fuels come from?
Comes from sulfur impurities.
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Why is acid rain bad?
It causes lakes to become acidic and many plants and animals die as a result. Acid rain kills trees and damages limestone buildings and ruins stone statues. Links between acid rain and human health problems have been suggested.
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How can you test for water?
Cobalt chloride paper. If the blue paper turns pink, it means water is present. But it doesn't mean that the water is pure.
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How can totally pure water be produced?
By distillation.
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What treatment does water go through at reserviors?
1) water passes through mesh screen; removes big bits. 2) chemicals added to make solids and microbes stick and fall to bottom. 3) water filtered through gravel beds; removes all solids. 4) water chlorinated to kill any harmful microbes left.
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Why is fluoride added to drinking water?
As it helps to reduce tooth decay.
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Why is chlorine added to drinking water?
To kill microbes and prevent disease.
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What are the disadvantages of adding chlorine to drinking water?
Has been linked to an increase in certain types of cancer.
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What are the disadvantages of adding fluorine to drinking water?
In high doses, it can cause cancer and bone problems. People can't choose is it's added - its 'mass medicating' which is a moral question.
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What are the two main ways of prevents rusting on iron?
Barrier methods: e.g. painting/coating with plastic, oiling/greasing. Sacrificial method: by placing a more reactive metal with the iron. The water and oxygen will react with the more reactive metal instead of the iron.
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