Making ethanol

Question 1

renewable

Answer 1

can be replaced as it is used

Question 2

two methods of making ethanol

Answer 2

fermentation of sugars

hydration of ethene

Question 3

fermentation to produce ethanol

Answer 3

process relies on single-cell fungi called yeast
yeast cells contain enzymes that catalyse the conversion of glucose to carbon dioxide and ethanol

glucose → ethanol + carbon dioxide
C6H12O6 (aq) → 2C2H5OH (aq) + 2C02 (g)

Question 4

how to carry out fermentation

Answer 4

temperature is two low - yeast cells become inactive
above 50°C - their enzymes become denatured and stop working
this means fermentation is carries out at about 35°C under normal atmospheric pressure

Question 5

non-renewable

Answer 5

used faster that it can be replaced

Question 6

hydration of ethene to produce ethanol

Answer 6

ethane is obtained from crude oil - non-renewable raw material
ethanol can be produced by the hydration of ethene

ethene + steam ⇌ ethanol
C2H4 (g) + H2O (l) ⇌ C2H5OH (g)

Question 7

conditions chosen for producing ethanol by the hydration of ethene

Answer 7

temperature of 300°C
pressure of 60 atmosphere
in the presence of phosphoric acid catalyst

Question 8

cost of raw materials

Answer 8

fermentation of sugars - low

hydration of ethene - high

Question 9

conditions

Answer 9

fermentation of sugars - moderate temperature, normal pressure
hydration of ethene - high temperature, high pressure

Question 10

energy requirements

Answer 10

fermentation of sugars - low

hydration of ethene - high

Question 11

rate of reaction

Answer 11

fermentation of sugars - low

hydration of ethene - high

Question 12

percentage yield

Answer 12

fermentation of sugars - low - about 15%

hydration of ethene - high - about 95%

Question 13

purity of product

Answer 13

fermentation of sugars - low - needs filtering and fractional distillation
hydration of ethene - high - there are no by-products