OCR chemistry

What is a hydrocarbon?
A hydrocarbon is a compound containing hydrogen and carbon only.
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What is fractional distillation?
Fractional distillation separates a mixture into a number of different parts, called fractions. A tall fractionating column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool
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What happens when you go up a fractionating column?
Lower boiling points (the greater the number of carbon atoms, the more heat needed to break the bonds), lower viscosity (they flow more easily), higher flammability (they ignite more easily).
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Name the fractions in fractional distillation...
Bitumen, Fuel oil, Disel, Kerosene, Gasoline, Petrol, LPG
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What is LPG made of?
Propane and Butane gases
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Name some fossil fuels...
Crude oil, Natural gas, Coal
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Describe non-rewnable fuels...
Non-rewnable fuels are ones which take a long time to make and are used up quicker than they are formed.
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Describe some environmental promblems involved in the exportation of crude oil...
1) Oil sinks to the bed as a result of accidents 2) Crude oil leakage can damage wildlife and birds' feathers. 3) use of detergents to clean up oil slicks and consequent damage to wildlife.
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Explain in simple terms the political problems associated with the exploitation of crude oil?
• UK dependent on oil and gas from politically unstable countries • future supply issues
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Describe the problems ascoiated with the finite nature of crude oil?
All the readily extractable resources will be used up in the future • finding replacements • conflict between making petrochemicals and fuels.
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Describe cracking...
Converts large alkane molecules into smaller alkane and alkene molecules. Makes useful alkene molecules that can be used to make polymers. Easy to ignite.
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Which two processes break down the covalent bonds in the molecules, causing thermal decomposition reactions.
-Heated to 600-700°C -Passed over catalyst of silica or alumina
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What is an alkane?
A family of hydrocarbons that share the same general formula
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State the rule of an alkane?
CnH2n+2
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Properties of Alkanes...
Saturated (This means that their carbon atoms are joined to each other by single covalent bonds. This makes them relatively unreactive, apart from burning or combustion, which is their reaction with oxygen in the air)
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What is an alkene?
A family of hydrocarbons that share the same general formula
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State the rule of an alkene?
CnH2n
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Properties of Alkenes...
Alkenes are unsaturated hydrocarbons. They contain a double bond, which is shown as two lines between two of the carbon atoms. The presence of this double bond allows alkenes to react in ways that alkanes cannot. They can react with oxygen in the air
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Name all the number prefixes of alkenes and alkanes...
meth-1 eth-2 pro-3 but-4 pent-5 hex-6 hept-7 oct-8 non-9 dec-10
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Describe the test to differeciate between alkenes and alkanes...
Bromine water is a dilute solution of bromine that is normally orange-brown in colour, but becomes colourless when shaken with an alkene. Alkenes can decolourise bromine water, while alkanes cannot as they do not have bonds to add on to.
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What are polymers?
Polymers are very large molecules made when many smaller molecules join together, end-to-end. The smaller molecules are called monomers
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Describe additional polymersation...
A process in which many alkene monomer molecules react together to give a polymer which requires high pressure and a catalyst. Its the addition of unsaturated molecules.
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Recognise the displayed formula for a polymer...
Ethene can polymerise to form poly(ethene), which is also called polythene. Propene can polymerise to form poly(propene), which is also called polypropylene.
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What is meant by a complete combustion of a hydrocarbon...
Complete combustion happens in a plentiful supply of air. Complete combustion releases more energy than incomplete combustion.
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What is meant by a incomplete combustion of a hydrocarbon...
Incomplete combustion occurs when the supply of air is limited. Incomplete combustion also creates carbon monoxide, and more soot.
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Describe complete combustion...
Complete combustion needs a plentiful supply of air so that the elements in the fuel react fully with oxygen. Fuels such as natural gas and petrol contain hydrocarbons -the carbon oxidises to carbon dioxide -the hydrogen oxidises to water
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What is the word equation of complete combustion?
hydrocarbon + oxygen → carbon dioxide + water
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Describe incomplete combustion...
Incomplete combustion occurs when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced instead of carbon dioxide.
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What is the word equation of incomplete combustion?
hydrocarbon + oxygen → carbon monoxide + carbon + water
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Other cards in this set

Card 2

Front

What is fractional distillation?

Back

Fractional distillation separates a mixture into a number of different parts, called fractions. A tall fractionating column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool

Card 3

Front

What happens when you go up a fractionating column?

Back

Preview of the front of card 3

Card 4

Front

Name the fractions in fractional distillation...

Back

Preview of the front of card 4

Card 5

Front

What is LPG made of?

Back

Preview of the front of card 5
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Comments

nankri1416

Very useful.

must use

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