CO₂ is Produced During Respiration

To show that CO₂ is produced during respiration with the use of KOH and Ca(OH)₂.

1. Take enough quantity (~150g) of germinating seeds. Put them into a conical flask. 

2. Tie a thread to the ignition test tube and fill it with KOH solution or pellets. 

3. Insert a bent tube through a one-holed cork and fix it to the opening of the conical flask along with the ignition tube as shown in the figure. 

4. Keep the other end of the bent tube dipped in a beaker containing water. 

5. Mark the water-level in the bent tube. Keep the whole set for 1-2 hours as such without disturbing. 

1. Respiring germinating seeds produce CO₂. 

2. The CO₂ is absorbed by the KOH pellets kept in the ignition test tube. 

3. The air from the bent tube moves into the conical flask. 

4. To fill the gap, the water level in the bent tube rises up. 

1. Take enough quantity (~150g) of germinating seeds. Put them into a conical flask. 

2. Insert a bent tube into the conical flask into the rubber cork and at another end into the beaker containing Ca(OH)₂. 

3. Keep the whole set up for 1-2 hours without disturbing and record your observations. 

The lime water turns milky when it comes into contact with CO₂.

1. Use freshly prepared Ca(OH)₂ and KOH solutions. 

2. Use fresh germinating seeds.