Alcohols
7 marks · HardEthanol can be produced via different industrial methods. One method involves the hydration of ethene, and another involves fermentation of sugars.
State the word equation for the hydration of ethene to form ethanol.
Write the balanced symbol equation for this reaction.
Fermentation is an alternative method for producing ethanol. List two advantages of using fermentation compared to hydration of ethene.
State one disadvantage of ethanol production by fermentation and one disadvantage of ethanol production by hydration of ethene.
Explain why some countries prefer one method over the other for ethanol production.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) ethene + steam → ethanol · must show correct word equation, reactants and products in correct order
(b) \ce{C2H4(g) + H2O(g) -> C2H5OH(g)} · must show balanced symbol equation
(c) Uses renewable resources; needs mild conditions; (any two advantages: renewable, low energy, mild temperature/pressure, etc.) · must show two valid advantages
(d) Fermentation: slow, impure product, batch process; Hydration: uses non-renewable resources, needs high energy/temperature/pressure (any one for each) · must show one disadvantage for each method
(e) Availability of raw materials (oil or sugar), e.g. oil-rich countries use hydration; countries with sugar crops use fermentation. · must show reason linked to resources, cost, or efficiency
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correct word equation for hydration of ethene
B2 (b) · 1 mark · Correct balanced symbol equation
B3 (c) · 2 marks · Any two valid advantages of fermentation over hydration
B4 (d) · 2 marks · One valid disadvantage of fermentation and one of hydration stated
B5 (e) · 1 mark · Clear explanation linking method choice to resources, cost or efficiency
Worked solution
a) The word equation is: ethene + steam → ethanol
b) The balanced symbol equation is:
c) Two advantages of fermentation are: it uses renewable resources (e.g. sugar cane), and it requires milder temperature and pressure compared to hydration.
d) One disadvantage of fermentation is that it is slow and produces impure ethanol. One disadvantage of hydration is that it uses non-renewable petroleum (oil) and needs high temperature and pressure.
e) Countries that have lots of oil use hydration because ethene is made from oil; countries with lots of sugar grow crops and use fermentation.