A group of compounds with the same general formula. The compounds contain the same elements and have similar molecular structures.
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What is the formula for alkanes?
CnH2n+2 (e.g. Butane has 4 carbons and 10 hydrogens)
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What is the formula for alkenes?
CnH2n (e.g. Propene has 3 carbons and 6 hydrogens)
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What is the formula for alcohols?
CnH2n+1OH (e.g. Methanol has 1 carbon, 3 hydrogens and an OH on the end)
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What is the formula for carboxylic acids?
CnH2n+1COOH
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What is fermentation?
The process of using yeast to convert carbohydrates into alcohol.
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What is often used as the carbohydrate source?
Sugar cane or sugar beet.
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When does fermentation happen fastest?
Between 30 and 40 degrees celsius.
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Why must the mixture be kept in anaerobic conditions?
Oxygen converts the ethanol into ethanoic acid otherwise (which tastes like vinegar)
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What happens when the concentration of the alcohol reaches about 10-20%?
The reaction stops because the yeast is killed off by the alcohol.
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How can a concentration of above 20% alcohol be obtained?
Fractional distillation must be used to separate the fermentation mixture
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How does this work?
Ethanol has a lower boiling point than water so when the mixture is heated, the ethanol evaporates and the vapour rises up the fractioning column. The water stays as a liquid.
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What is used to liquefy the ethanol again?
A condenser is used which cools the ethanol vapour.
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What are the pros and cons of fermentation?
It uses a renewable energy resource but the quality of the ethanol isn't good and it is expensive to concentrate and purify.
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Other cards in this set
Card 2
Front
What is the formula for alkanes?
Back
CnH2n+2 (e.g. Butane has 4 carbons and 10 hydrogens)
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