✅C6.1.5 ethanol only

Question 1

what are the two methods of making ethanol? (and describe each one briefly)

Answer 1

fermentation - using yeast to catalyse the conversion of glucose solution to carbon dioxide and ethanol

hydration - obtaining ethene from crude oil and reacting it with steam

Question 2

why is yeast added to the glucose solution in order for it to ferment?

Answer 2

as it contains enzymes which catalyse the conversion of glucose to ethanol and carbon dioxide

Question 3

positives of using fermentation?

Answer 3

• has a renewable resource (plant sugars)
• can carry out in a school lab

NOT A REVERSIBLE REACTION

Question 4

conditions for fermentation to take place? (and explain why)

Answer 4

• not a reversible reaction
• 35C (too low = yeast cells inactive, too high(above50) = enzymes denature)
• atmospheric pressure

Question 5

**what is the word equation for hydration to occur (to produce ethanol)?

Answer 5

ethene + steam ⇌ ethanol

-45 kJ/mol

Question 6

**what are the conditions needed for hydration to produce ethanol?

Answer 6

• 300C
• 60 atmospheres
• phosphoric acid catalyst
• therefore cannot occur in a school laboratory
• exothermic reaction

REVERSIBLE REACTION

Question 7

**compare fermentation of sugars and hydration of ethene (6)

Answer 7

fermentation
- low raw material cost

• normal pressure + temp
• low energy needed
  BUT
• low percentage yield
• low rate of reaction
• low purity (more energy needed to extract product further; needs filtering and fractional distillation)

hydration 
- high material cost 
- high pressure + temp 
- high energy needed 
BUT 
- high percentage yield (95%) 
- high purity (no by-products)

Question 8

**Fermentation word and symbol equations

Answer 8

Glucose —> carbon dioxide + ethanol

C6H12O6 (aq) —> 2 CO2(g) + 2 C2H5OH (aq)

Question 9

**Hydration of ethene word and symbol equations

Answer 9

Ethene + steam ⇌ ethanol

C2H4(g) + H2O(g) ⇌ C2H5OH(g)