How can the gases in the air be separated from liquid air?
By fractional distillation
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What are the stages of fractional distillation of air?
Firstly, the air is compress to about 150 times atmospheric pressure. Then the pressure is released and the temperature drops. Water and carbon dioxide can easily be removed from the mixture before the liquid air mixture is passed into the fractionin
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How can the different gases be separated?
The column is colder at the top than it is at the bottom so nitrogen boils off first and is passed out of the top of the column. Oxygen is separated off as a liquid at the bottom of the column. Agron is collected between them.
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What do the metallic elements burn to form?
Solid oxides
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What do non-metallic elements burn to form?
Oxides that are produced as gases
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What are reactions with oxygen to form oxides known as?
Combustion reactions
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In general, what are metal oxides?
Baisc
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In general, what are metal oxides?
Alkalis
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In general, what are non-metal oxides?
Acidic
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What are water and carbon monoxide?
Neutral
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What are amphoteric bases?
Oxides that behave both like acids and bases
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What are the three main stages in producing water that is fit to drink?
1) Water from an appropriate source can be treated 2) Water is treated by sedimentation and filtration to remove solids 3)It is then sterilized to kill microbes
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What is desalination?
Converting seawater into useable water
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What happens in desalination?
Seawater undergoes distillation at an industrial plant, but at a reduced pressure to lower the boiling point and save energy
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How do water filters work?
Water is passed through a filter cartridge that contains activated carbon, an ion-exchange resin and silver
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What does the carbon do?
It reduces the levels of chlorine left in the water as carbon has a slightly positive charge which means impurities stick to it
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What does the ion-exchange resin do?
Removes calcium, magnesium, lead, copper and aluminium ions
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What does the silver do?
Discourage the growth of bacteria in the filter
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What is rust?
Rust is a form of iron(iii) oxide called hydrated iron(iii) oxide
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What is the word equation for rust?
iron+oxyen+water ----> hydrated iron(iii) oxide
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What two things are needed for rusting to take place?
Water and air (oxygen)
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What are some methods of preventing rust?
Coating the iron with: paint, oil, grease, plastic, a less reactive metal or a more reactive metal
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What is sacrificial protection?
A method of protection against rusting by connecting to, or adding a thin coating of a metal which is more reactive than iron, such as zinc or megnesium
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Other cards in this set
Card 2
Front
What are the stages of fractional distillation of air?
Back
Firstly, the air is compress to about 150 times atmospheric pressure. Then the pressure is released and the temperature drops. Water and carbon dioxide can easily be removed from the mixture before the liquid air mixture is passed into the fractionin
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