Question

Give an activity to show that carbon dioxide is given out during respiration.

Answer 1

$Aim :$

To show that Carbon Dioxide (CO2) is given out during respiration.


$Apparatus :$

Seeds, Conical flask, delivery tube, test tube, beaker, coloured water, potassium hydroxide, candle.


$Procedure :$


Put some germinating seeds in a conical flask.

The conical flask is fitted to a delivery tube bent twice at right angles by means of cork.

Suspend a small test tube containing 20% potassium hydroxide.

Dip the free end of the bent tube in a beaker of coloured water.

Leave it for a day. Note the changes.

The germinating seeds respires aerobically by utilizing the oxygen in the flask.

Carbon dioxide released during the aerobic respiration is absorbed by potassium hydroxide and creates a vacuum and causes rise of water in the bent tube.

If we put a burning candle in the setup, the candle extinguishes which proves oxygen is utilized by germinating seed for respiration.

$Observation :$



Carbon dioxide given by germinating seeds is absorbed by Potassium hydroxide during respiration experiment.

This creates a vacuum in the conical flask.

And we will see that the air present in the bent glass tube moves into the conical flask.


$Conclusion :$

Carbon dioxide gas turns limewater milky.

Therefore the fact that the carbon dioxide gas is produced during respiration can be shown by demonstrating the effect of inhaled air and exhaled air on lime-water.

From the experiment, we come to know that the tube containing inhaled air is less milky while the tube with exhaled air is milkier.

From Thia we also see also conclude that less the carbon dioxide is present in inhaled air but much more the carbon dioxide is present in exhaled air.

And also from this observation we conclude that carbon dioxide is produced during respiration (which comes out in exhaled air).