Chemistry 1 OCR TWENTYFIRSTCENTURY

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  • Created by: Tami
  • Created on: 15-05-16 22:13
What is the air made of?
78% Nitrogen, 21% oxygen, 1% is mainly argon (this includes small parts of (0.04%)carbon dioxide and water vapour)
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When was the earth's atmosphere formed?
4 billion years ago by gas given out by volcanoes
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What do volcanoes release?
They release huge amounts of carbon dioxide and water vapour.
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What processes removed the carbon dioxide from the early atmosphere and left the air with the composition we have today?
-Four billion years ago the earth's atmosphere was hot and as it cooled,oceans formed from the condensed water -3 billion years ago simple-like bacteria evolved and began to photosynthesize
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Continued answer from last question...
-This removed the Carbon dioxide and released oxygen, allowing animals to evolve -carbon dioxide was removed by plants and animals dying and becoming buried. -over millions of years some of the buried material became fossil fuels
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Continued ....
- carbon dioxide dissolved in oceans reacts with salt to form insoluble calcium carbonate. - This forms sediments to which become buried and cemented to form sedimentary rock.
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Name some human activities that are changing the gases in the atmosphere?
Burning of fuels in factories, power stations, for transport and in homes
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Name some pollutants
carbon monoxide, nitrogen oxides and sulfur dioxide
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Carbon dioxide is linked to climate change.. why?
Carbon dioxide is a greenhouse gas to which absorbs and re-emits the heat radiation and as a result of this the atmosphere gets warmer.
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What is the green house effect?
The greenhouse effect is the natural process by which the atmosphere traps some of the Sun's energy, warming the Earth enough to support life.With the increase of greenhouse gases more of the heat emitted by the earth (from the sun) is being trapped.
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Why are sulfur dioxide and nitrogen dioxide pollutants?
They both create acid rain to which damages plants and kills animals
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What are the effects of solid particulates (carbon)?
They trigger asthma for some people.(respiratory problems)
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Effects of carbon monoxide?
Carbon monoxide is a toxic gas to which reduced the amount of oxygen blood can carry.
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What is oxidation?
When oxygen is added to a substance
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what is reduction?
When oxygen is removed from a substance.
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What type of reaction is combustion?
combustion is an oxidation reaction
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What is the word equation for the burning of a hydrocarbon?
hydrocarbon fuel + oxygen ---> carbon dioxide + water (+energy)
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what are the products of incomplete combustion?
carbon monoxide and carbon particulates are formed during incomplete combustion (limited amount of oxygen in the air)
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Write the word equation for the burning of sulfur in a fossil fuel?
sulfur + oxygen ---> sulfur dioxide (coal contains the most sulfur and can give off more sulfur dioxide than other fuels)
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How are nitrogen oxides formed?
Nitrogen and oxygen from the air react together under the high temperatures of a cars engine to for nitrogen oxides
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Why is Nitrogen dioxide bad?
It is a toxic brown gas
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Name ways to reduce our fossil fuel use?
-use alternate renewable energy sources - using public transport - cycling and walking - using biofuels that are made from plants
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Define carbon neutral (biofuels are carbon neautral)
When they are burned they release the same amount of carbon dioxide that the plant originally took from the air to grow.
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Ways air pollution by cars can be reduced are:
- using cars less frequently using cleaner fuels and removing pollutants from exhaust - making public transport cheaper, more frequent and available in more places
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What are catalytic converters?
They contain a platinum catalyst to which allows pollutant gases to react with each other . carbon monoxide + nitrogen monoxide --> nitrogen + carbon dioxide
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What is the word equation for the reaction of carbon monoxide and nitrogen monoxide?
Carbon monoxide + nitrogen monoxide --> carbon dioxide + nitrogen
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What is flue gas desulfurisation (wet scrubbing) ?
1) using an alkaline slurry of calcium oxide (lime) and water to make gypsum (calcium sulfate)
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Name another wet scrubbing method?
2) using seawater (a natural alkaline that absorbs sulfur dioxide)
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What are plasticisers ?
They are used to make a polymer softer. they are small molecules inserted into polymer chains to keep them apart, weakening the forced between them.
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What are thermoplastics?
They soften when heated and can be moulded into shape.
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What are crosslinks?
They lock the molecules together so they cannot melt.
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What is crystallinity?
It refers to the degree of structural order in a solid.
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What is a melting point?
It is the temperature at which a solid turns to liquid.
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What is tensile strength?
The force needed to break a material when it is being stretched.
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What is stiffness?
The force needed to bend a material
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What is density?
The mass of a given volume.
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What is compressive strength?
The force needed to crush a material when it is being squeezed.
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What are metals?
They are chemicals to which are malleable and electrical conductors.
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What is are composites?
They are nano particles mixed with other materials. eg They are used tennis balls to make them stay bouncy for longer
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What are rocks?
They are raw materials found in the Earth's crust E.G limestone, coal and salt
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How was limestone formed?
- Shellfish died forming sediments -sediments compact and harden to form limestone a sedimentary rock - Tectonic plate movement push the rock to surface -gradually rocks above eroded away and exposes limestone.
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How was coal formed?
Coal was formed in swampy wet conditions when plants lie trees and ferns died and became buried. This excluded oxygen slowing down the decay.
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How was salt formed?
salt formed while Cheshire was covered by shallow sea: - rivers brought dissolved salts into the sea -climate chage evaporated the water, leaving salts that mixed with sand blown in by the wind. - rock salt formed and buried by other sediments
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What evidence do Geologists have form the formation of limestone, salt and coal?
-coal contains fossils of plants that formed it -limestone contains bits of shell fragments from sea creatures -rock salt contains different shaped water-eroded grains and wind-eroded grains.-ripple marks indicate waterflow.
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How can salt be obtained?
-collecting and evaporating sea water -mining underground deposits of rock salt.
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What are alkalis and what do they do?
They are soluble metal hydroxide and soluble metal carbonates that have a PH of above 7
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What are alkalis used for?
dying cloth, neutralising acid soils, making soap and making glass
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What is the word equation for neutralisation?
acid+alkaline---> salt + water
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What was the Leblanc process and why was it a bad thing?
it was the reacting of salt with limestone to create sodium carbonate (heated with coal). -It gave off large amount of hydrogen chloride(a harmful and acidic gas) -it also produced solid waste called galligu that released hydrogen sulfide (toxic gas)
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What are bases?
Insoluble metal hydroxides and metal carbonates
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What is the word equation for a reaction with a base and an acid?
hydroxide + acid---> salt + water OR carbonate + acid---> water + carbon dioxide gas
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Name a use for all the products of electrolysis?
hydrogen for making margarine, chlorine for bleach, sodium hydroxide for industrial cleaners
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Other cards in this set

Card 2

Front

When was the earth's atmosphere formed?

Back

4 billion years ago by gas given out by volcanoes

Card 3

Front

What do volcanoes release?

Back

Preview of the front of card 3

Card 4

Front

What processes removed the carbon dioxide from the early atmosphere and left the air with the composition we have today?

Back

Preview of the front of card 4

Card 5

Front

Continued answer from last question...

Back

Preview of the front of card 5
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