Alcohol production

Question 1

Give two ways of alcohol production

Answer 1

1. hydration of alkenes using an acid catalyst eg H3PO4
   hydration: high temp (300), high pressure
2. ethanol produced via fermentation of glucose
   fermentation: cheaper than hydration, slower, lower percentage yield, needs yeast

ethanol can be separated via fractional distillation –> used as a biofuel which is carbon-neutral.

Question 2

how is ethanol carbon-neutral?

Answer 2

the carbon given out when it is burned is equal to the carbon taken in by crops during the growing process.

Question 3

explain the meaning of the term biofuel

Answer 3

a fuel produced by plants

Question 4

write equations to support the statement that ethanol produced by fermentation is a carbon neutral fuel

Answer 4

Removal of CO2 by photosynthesis
6CO2 + 6H2O➜ C6H12O6 + 6O2

Production of CO2 by fermentation and combustion
C6H12O6 ➜ 2CH3CH2OH + 2CO2
2CH3CH2OH + 6O2➜ 4 CO2 + 6 H2O

*NO NET RELEASE OF CO2

Question 5

outline the mechanism for the formation of an alcohol by the reaction of an alkene with steam in the presence of an acid catalyst

Answer 5

Question 6

discuss the environmental (including ethical) issues linked to decision making about biofuel use.

Answer 6

This does not take into account the energy needed to irrigate plants, fractionally distil the ethanol from the reaction mixture or process the fuel.

If the energy for these processes comes from fossil fuels then the ethanol produced is not carbon neutral.