Ethanol production

Question 1

Why are alcohols important in industrial chemistry?

Answer 1

used as intermediated easily made and converted into other compounds

Question 2

What are the uses of ethanol?

Answer 2

intermediate in the manufacture of other organic chemical

used as a solvent in cosmetics, e.g. aftershave and perfumes

also used to manufacture drugs, detergents, inks and coatings

Question 3

How is it made in industry?

Answer 3

reacting ethene (from cracking crude oil) with steam, using a catalyst of phosphoric acid

Question 4

How is it made from sugar?

Answer 4

by fermentations, as in the production of alcoholic drinks

Question 5

What is the mechanism for making ethanol from ethene?

Answer 5

1. an electron is transferred from the double bond to a H⁺ ion
2. an electron from the lone pair of a partially negative oxygen in a water molecule is attracted to the carbocation
3. an electron from the O⁺ - H bond moves to the oxygen and an H⁺ ion is released

Question 6

How is ethanol made by fermentation?

Answer 6

carbohydrates from plants are broken down into sugars and then converted into ethanol by the action of enzymes from yeast

the carbohydreates come from crops such as sugar cane and sugar beet

Question 7

What is the equation for fermentation?

Answer 7

anaerobic respiration

C₆H₁₂O₆ (aq) → 2C₂H₅OH (aq) + 2CO₂ (g)

Question 8

What are the conditions for fermentation?

Answer 8

rate is determined by temperature, it is slow at low temperatures, but enzymes are made ineffective at a temperature too high

air is kept out of fermentation vessels to prevent oxidation of ethanol to ethanoic acid (the acid in vinegar)

once the fermenting solution contains about 15% ethanol the enzymes are unable to function and fermentation stops, ethanol may then be distileed by fractional distallation

Question 9

Compare the benefits of using crude oil or carbohydrates to produce ethanol

Answer 9

crude oil is faster, it is continuous whereas fermentation is batch and it is pure

Question 10

Why is fermentation better?

Answer 10

it is carbon neutral and reneqable