Worksheet: Fermentation of Ethanol

In this worksheet, we will practice writing an equation for ethanol formation by fermentation and explaining the roles of yeast, glucose, and temperature in the process.


What must be added to a glucose solution for fermentation to occur?

  • ACarbon dioxide
  • BOxygen
  • CAcid
  • DSalt
  • EYeast


In which of the following temperature ranges does yeast typically produce the highest rate of fermentation?

  • A2530C
  • B510C
  • C4550C
  • D3540C
  • E1520C


What must be excluded from a fermenting material to allow the reaction to take place?

  • ASound
  • BLight
  • CWater
  • DOxygen
  • ECarbon dioxide


In the absence of oxygen, yeast converts glucose to ethanol. Muscles, when starved of oxygen, can extract a small amount of energy from glucose by converting it to an organic compound. What is that compound?

  • AEthanol
  • BVitamin C
  • CCarbonic acid
  • DSucrose
  • ELactic acid


Yeast is added to bread dough to convert glucose in the dough to carbon dioxide gas, which helps the bread rise. Another product of this reaction is ethanol. Why is the ethanol content of baked bread very low?

  • AEthanol is a liquid, so it leaks out of the bread during baking.
  • BEthanol is volatile, so it evaporates from the bread during baking.
  • CEthanol combusts during baking, producing water and carbon dioxide.
  • DEthanol reacts with proteins during baking, producing compounds that color and flavor the bread.
  • EEthanol reacts with itself during baking, producing lactic acid and water.


Which of the following is a disadvantage of producing ethanol through fermentation, rather than through the addition reaction of ethene?

  • ALow pressure is required for this reaction to proceed.
  • BThe reaction solution must be slightly acidic.
  • CThe required temperature for fermentation is 37C.
  • DThe reaction happens under anaerobic conditions.
  • EThe percentage yield is around 15%.


Which of the following features of the production of ethanol from ethene is an advantage?

  • APressure of 70 atm
  • BEthene comes from crude oil.
  • CTemperature of 300C
  • DThick steel reaction vessels are used.
  • EThe rate of reaction is fast.


Which chemical is produced from the fermentation of sugar?

  • AEthane
  • BEthanol
  • CMethane
  • DEthene
  • EMethanol


Which of the following is not required to form ethanol through fermentation?

  • ALight
  • BYeast
  • CWater
  • DSugar
  • EOxygen


Why is the yield of ethanol produced by fermentation limited to around 15%?

  • AThe glucose from the plants runs out.
  • BThe alcohol concentration starts to kill the yeast and no more ethanol is produced.
  • CThe alcohol starts to evaporate more quickly at higher concentrations.
  • DThe batch process is stopped and restarted at 15%.
  • EThe temperature of the reaction mixture drops due to the greater concentration of ethanol.


Give the correct values for 𝑥 and 𝑦 in the following equation describing fermentation. CHOCHOH+CO6126252𝑥𝑦

  • A1, 2
  • B3, 1
  • C2, 1
  • D1, 3
  • E2, 2


Sugar is fermented with yeast to produce ethanol. What happens to the speed of fermentation as the temperature is raised from 0C to 100C?

  • AIt stays the same.
  • BIt decreases.
  • CIt decreases then increases.
  • DIt increases.
  • EIt increases then decreases.

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