Chemistry Topic 3

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What are alkanes?
Hydrocarbons (molecules made of only hydrogen and carbon). Chains of carbon atoms surrounded by hydrogen atoms. CnH2n+2 , homoglous series.
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Complete combustion of alkanes.
alkane + oxygen -> carbon dioxide + water + (energy). (EG- methane. CH4+2O2->CO2+2H2O).
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Incomplete combustion of alkanes.
alkane + oxygen -> carbon + carbon monoxide + carbon dioxide + water + (energy). Makes smokey yellow flame, less energy than complete. (EG 4CH4+6O2->C+2CO+CO2+8H2O)
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How are haloalkanes made with alkanes?
Halogens react with alkanes in the presence of ultraviolet light. A hydrogen atom from the alkane is substituted by chlorine/bromine (SUBSTITUTION REACTION), making bromomethane. Methane+brome->bromoethane + hydrogen bromide.
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What are alkenes?
Hydrocarbons with a carbon-carbon double bond. Unsaturated molecules, can make more bonds. CnH2n, homoglous series.
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How are haloalkanes made with alkenes?
EG dibromoethane. Addition reaction, C=C double bond split, halogen atom added to each of carbons. ethene+bromine->dibromoethane. Shake alkene with orange bromine water, solution will be colourless-test.
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How is ethanol made from crude oil?
Produced from cracking crude oil. C2H4+H2O->C2H5OH. ethene+stem->ethanol. Temp 300degreesC, 60-70atm. Phosphoric acid catalyst. Very fast,pure, finite resource, continuous process at high temp and pressure. Expensive equipment, low labour costs.
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How is ethanol made from fermentation?
Raw material for fermentation is sugar, converted into ethanol using yeast. 30degreesC. Very slow, very impure. Sugar is a renewable resource. batch process at lower temp, cheap equipment, high labour costs.
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How can ethanol be dehydrated from ethene?
Remove water from the ethanol in a dehydration reaction. Ethanol vapour is passed over a hot catalyst of aluminium oxide, catalyst provides large surface area for reaction. C2H5OH->C2H4+H2O
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Other cards in this set

Card 2

Front

Complete combustion of alkanes.

Back

alkane + oxygen -> carbon dioxide + water + (energy). (EG- methane. CH4+2O2->CO2+2H2O).

Card 3

Front

Incomplete combustion of alkanes.

Back

Preview of the front of card 3

Card 4

Front

How are haloalkanes made with alkanes?

Back

Preview of the front of card 4

Card 5

Front

What are alkenes?

Back

Preview of the front of card 5
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