Experiment showing Oxygen is evolved during photosynthesis?

Requirements:

Apparatus: beaker, test tube, funnel, glass rod, etc.

Materials: An aquatic plant e.g. Hydrilla, matchstick.

Chemical: Water, sodium, bicarbonate, pyrogallic solution.

Theory:  Photosynthesis (G. K photo- light, synthesis-production) is the anabolic process in which green plants produced their food in the presence of sunlight and chlorophyll and produce glucose and oxygen. The volume of oxygen released during photosynthesis is co-equal to the volume of carbon dioxide absorbed. The released oxygen is exclusively formed from the water and not from carbon dioxide. The processes of photosynthesis can be represented by the following chemical equation.

The overall reaction is not a single and simple reaction between carbon dioxide and water but a higher complex process in which a number of reactions occur. In it, the radiant energy absorbed by chlorephy11 is transferred into chemical energy which is available for all vital activities of living cells. Photosynthesis consists of oxidation and reduction. The overall process of photosynthesis. Is completed into two main phases.

1. Light reactions or Hill reaction
2. Dark reaction or Blackman reaction

Procedure: A few branches of an aquatic plant Hydrilla are kept in a big beaker full of the same pond water. Thereafter the branches are covered with a test tube full of water is inverted at the end of the funnel. If rewired a small quantity of sodium bicarbonate may be added to the water. So that the supply of carbon dioxide may become adequate for photosynthesis. Now, the apparatus is kept in the sunlight.

Observation: the gas bubbles may be observed from the ends of the Hydrilla branches kept under the glass funnel. In the beaker. These gas bubbles are accumulated at the end of the test tube inverted at the end of the funnel. and the water within the tube goes downward.

Test of oxygen Gas: the presence of oxygen gas can be tested by introducing a few drops of pyrogallate solution into the test tube. The pyrogallate solution absorbs oxygen immediately and the tube gets refilled with water. It can also be tested by introducing a burning stick.

Result and conclusion: The pyrogallic acid has the property of absorbing oxygen gas. When pyrogallate acid introduction into the test tube, it absorbs oxygen gas collected at the top of the test tube creating a partial vacuum and water up filing the vacuum. It concluded that the released gas during photosynthesis is oxygen.

Precautions:

1. Set up should be kept in sunlight.
   
   
2. The plant should be completely dipped in water.
   
   
3. The inverted test tube should be complete.
   
   
4. The funnel should be raised from the bottom of the beaker by keeping wooden support to maintain the flow of the CO₂ source.