Making Ethanol

C7 Revision

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Making Ethanol 1

Ethanol can be made by fermentation;
sugar     -->     ethanol + carbon dioxide
Happens fastest at 30 degrees C, pH 4, prevent oxygen getting in, when ethanol reaches 10 to 20% the fermentation reaction stops as the yeast is killed of by the ethanol.
Ethanol solution can be concentrated by distillation
The fermented mixture can be distilled to produce more concentrated ethanol;
Put in a flask below a fractioning column, heated up so the ethanol boils and the vapour travels up the column, the ethanol cools to a liquid and flows back into the solution at the bottom, only the pure vapour reaches the top of the column, the vapour flows through a condenser then collected.
Look back at producing chemicals questions;
1) won't run out
2)low atom economy, less efficient
3) waste CO2 can be released
4) energy is need to keep the reaction at optimum temperature
5) CO2 is a greenhouse gas - global warming... 6) No danger
7) Doesn't impact the society..8) Depends, yes if drinking or fuel

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Making Ethanol 2

Ethanol can be made by biomass;
parts of plant that would be thrown away - corn stalks, straw etc, cannot be fermented in normal way as it contains a lot of cellulose, yeast can't convert the cellulose into ethanol, temperature - 35 degrees C with a pH 6.
The sustainability is similar to the normal fermentation, the advantage is you don't have to grow crop specially for producing ethanol.

Ethene can be reacted with steam to produce ethanol
Fermentation is too slow if making ethanol on a large scale.
1)Ethane = hydrocarbon found in crude oil
2) Split to form ethene (C2H4) and hydrogen (ethane - ethene + hydrogen)
3)Ethene will react with steam to make ethanol - (ethene+steam--ethanol)
4)Needs a temperature of 300 degrees Cand pressure of 70atmospheres, phosphoricacid is used as a catalyst.
1) Yes; 2) High; 3)Hydrogen gas; 4)High temp and pressure; 5) oil spills; 6)High temp and pressure is carefully controlled; 7) no specific; 8)Yes

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