Fermentation of glucose

Fermentation of glucose

ZIMSEC O Level Combined Science Notes: Experiment: making ethanol

Aim: To make ethanol by fermenting glucose

Materials: conical flask/plastic bottle, cork, glass/rubber tube,lime water, 5% glucose solution, yeast, mealie meal


  1. Add about 50cm3 of the 5% glucose solution into the flask
  2. Add a spatula of yeast/mix mealie meal with water and add to yeast
  3. Cork the flask and alow the end of the tube to dip in lime water in the test tube as shown in the diagram above
  4. Leave in a warm place for a few days
  5. Observe the lime water
  6. Smell the contents of the flask

Results and Observations

  • The lime water turns milky after a few days
  • The contents of the flask have a pungent smell typical of alcohol/ethanol


  • The glucose solution is turned into an ethanol solution by the fermentation process

NB The concentration of the alcohol can be increased via the distillation process

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