The by-product of the fermentation of sugar to ethanol is

JAMB Chemistry 2024 86 views

The by-product of the fermentation of sugar to ethanol is

  1. propane -1,2,3-triol
  2. ethyl ethanoate
  3. ethanedioc acid
  4. carbon (IV) oxide ✓

Explanation

Fermentation is the process where yeast (a microorganism) breaks down sugar (glucose) into ethanol and carbon (IV) oxide. Yeast produces an enzyme called zymase that acts as a biological catalyst for this reaction.

The equation for fermentation is:

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂

This means one molecule of glucose produces two molecules of ethanol (C₂H₅OH) and two molecules of carbon (IV) oxide (CO₂). The ethanol is the desired product, while the carbon (IV) oxide is the by-product (the extra product formed alongside the main product).

Fermentation happens at warm temperatures (about 25°C to 40°C) in the absence of oxygen (anaerobic conditions). If oxygen is present, the yeast will carry out aerobic respiration instead, producing CO₂ and water but no ethanol.

The other options are unrelated to fermentation. Propane-1,2,3-triol (glycerol) is found in fats and oils. Ethyl ethanoate is an ester made from ethanol and ethanoic acid. Ethanedioc acid (oxalic acid) is a dicarboxylic acid found in some plants.

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