Liberation of Carbon Dioxide gas during Fermentation

Materials Required

  • Two test tubes
  • Petroleum jelly 
  • Dropper 
  • Baker’s yeast 
  • Freshly prepared lime water 
  • Sugar solution
  • Cork with one hole 
  • Delivery tube 
  • Laboratory stand with clamp 


The Procedure

Real lab procedure

  • Fill one test tube with sugar solution. 
  • Dissolve the baker’s yeast in water in another test tube. Using dropper take 2mL of this suspension in the test tube filled with sugar solution. Smell the solution and record the smell. 
  • Fix the cork on the solution filled test tube. Make the test tube airtight by applying petroleum jelly. 
  • Insert the delivery tube through the cork into the test tube containing the liquid mixture.
  • Clamp the test tube in the laboratory stand. 
  • Place the other end of the delivery tube in freshly prepared lime water. 
  • Keep the set up undisturbed under sunlight for 60 minutes.
  • Again, smell the solution after 60 minutes. Record the smell. 

Simulator procedure

  • Drag and drop the dropper of 2mL of yeast solution to sugar solution.
  • Click on the next button to go to the next screen of simulator.
  • You can see the image of sugar solution with yeast solution in test tube and showing the smell coming out of it.
  • Drag and drop the cork on the test tube.
  • Drag and drop the test tube towards laboratory stand for clamping it.
  • Drag and drop the delivery tube and place it through the single-bore cork to the filled test tube.
  • Drag and drop the freshly prepared lime water in beaker towards the other end of the delivery tube.
  • Click on the next button to go to the next screen of simulator. 
  • You can see the movement of the clock showing 60 minutes along with sunlight.
  • Zooming and showing the beaker, you can see the air bubble passing through the lime water and the lime water turns milky. 
  • Click on the information icon to see the inference.  
  • You can redo the experiment anytime by clicking on the ‘Reset’ button. 



In lime water the air bubbles are observed, and the lime water turns milky due to the liberation of carbon dioxide gas.