To show that oxygen gas is released during photosynthesis
Plants use sunlight and carbon dioxide present in air to produce food for itself; one of the by products of this chemical reaction is the formation of oxygen. The fact that oxygen aids combustion makes it easy to identify this gas.
- Glass beaker
- Water rich in carbon dioxide
- Glowing splinter to test gas generated
Estimated Experiment Time
Approximately 10 minutes to set up the apparatus and 5-8 hours to carry out the observations
- 1. Fill a glass beaker with water rich in carbon dioxide
- 2. Place green water-weed (Elodea or Ceratophyllum) in this beaker
- 3. Place a funnel over the plant (encasing it)
- 4. Invert a test-tube filled with water over the funnel
- 5. Leave this set-up undisturbed in bright sunlight
Bubble carbon dioxide gas through water before using it to fill up the glass beaker for best results.
Bubbles of colorless gas are formed on the leaves after some time and are seen to rise and collect in the upper, closed part of the test-tube. On testing the gas by placing a glowing splinter in the tube, it bursts into flames.
The splinter caches fire because the gas released by the leaves is oxygen; hence oxygen is released during photosynthesis.
Take a moment to visit our table of Periodic Elements page where you can get an in-depth view of all the elements,
complete with the industry first side-by-side element comparisons!