Organic Chemistry: Ethanol

Question 1

Name two process that ethanol is produced by

Answer 1

• fermentation

- direct hydration of ethane

Question 2

Describe process of fermentation

Answer 2

• yeast added to sugar/starch solution in anaerobic conditions and temp of 25-40c
• enzymes in yeast convert sugar to ethanol and CO2

Question 3

How is ethanol obtained after fermentation?

Answer 3

• filtered to remove excess yeast

- fractional distillation

Question 4

Describe process of direct hydration of ethane

Answer 4

• mixture of ethane and steam passed over phosphoric acid at temp of 300c and atm pressure of 60-70
• condensed as a liquid
• unreacted ethane recycled back into process

Question 5

Ethanol production: resources

Answer 5

• fermentation: uses renewable resources (e.g. sugar)

- hydration: uses non-renewable resources (one crude oil is used up there will be no more

Question 6

Ethanol production: type of process

Answer 6

• fermentation: batch process at low temp - cheap equipment, but high labour costs
• hydration: continuous process at high temp and pressure using expensive equipment, but low labour costs

Question 7

Ethanol production: rate of reaction

Answer 7

• fermentation: very slow - takes several days for each batch
• hydration: very fast

Question 8

Ethanol production: quality of product

Answer 8

• fermentation: dilute solution of ethanol needing further processing
• hydration: produces pure ethanol

Question 9

What catalyst is used to dehydrate ethanol?

Answer 9

hot aluminium oxide- provides large SA for reaction

Question 10

What can dehydration be used for?

Answer 10

manufacturing ethene for production of polyethene