Give an experiment to prove that carbon dioxide is released during respiration.
Respiration is a biochemical process in which the food is oxidised in order to release energy.
To prove that CO 2 is released during respiration,
- We take germinating seeds which are actively respiring to produce CO 2 a
And we use
Potassium Hydroxide (KOH)
this released CO
The overall reaction is as follows:
Conical flask, U-shaped delivery tube (tube bent twice at right angles), cotton wool or moist blotting paper, water, thread, beaker, test tube, rubber cork with one hole, 20% freshly prepared KOH solution, vaseline, soaked gram seeds.
- Take about 25-30 seeds of gram and germinate these seeds by placing them on moist cotton wool or moist blotting paper for 3-4 days.
- Place the germinated seeds into a conical flask and sprinkle a little water in the flask to moist the seeds.
- Take freshly prepared 20% KOH solution in a test tube and hang it in a conical flask with help of thread.
- Close the mouth of the conical flask by placing a rubber cork containing one hole. .
- Through the hole of rubber cork, insert one end of the U-shaped glass delivery tube in the conical flask and place the other end into a beaker filled with water.
- Seal all the connections of the experimental set-up with vaseline so as to make it air-tight.
- Mark the initial level of water in the U-shaped delivery tube.
- Keep the apparatus undisturbed for 1-2 hours and note the change in level of water in the delivery tube.
The level of water in the U-shaped delivery tube dipped in water of the beaker rises after sometime.
- CO 2 is released by the germinating seeds during respiration in a conical flask.
- This CO 2 is absorbed by KOH which is hanging inside the conical flask.
- Due to absorption of CO 2 , a vacuum is created which causes an upward movement of water present inside the delivery tube which can be seen by change in level of water in that tube.
- Germinating seeds should be kept moist.
- All connections of the set-up should be air-tight.
- Freshly prepared KOH solution should be used.
- Keep one end of the U-shaped delivery tube in a conical flask and the other end immersed in water of the beaker.
- The test tube containing KOH should be hung carefully.