Question

Write the experiment to measure transpiration in plants using cobalt chloride paper.

Answer 1

Experiment showing transpiration
in plants using cobalt chloride paper.

Aim: To demonstrate the process of transpiration in plants using dry cobalt chloride paper.

Materials Required: Two healthy leafy potted plants, 3 polythene bags, 3 strips of dry cobalt chloride paper, 3 wooden sticks, and 3 glass bell jars.

Procedure:

1. Set-up A: Place a well-watered, broad-leaved potted plant under a bell jar. Before placing it, completely enclose the pot base with a polythene bag and tie it tightly around the stem base to prevent soil moisture from escaping.
2. Set-up B: Prepare a similar plant set-up as Set-up A, but also place a piece of dry blue cobalt chloride paper pinned to a wooden stick inside the jar next to the plant.
3. Set-up C (Control): Take an empty bell jar and place only a piece of dry blue cobalt chloride paper attached to a wooden stick inside it, without any plant. Keep all three setups out in the sunlight for about an hour.

Observation:

• In Set-up A, tiny droplets of water appear on the inner walls of the bell jar.
• In Set-up B, similar water droplets appear, and the blue cobalt chloride paper turns completely pink.
• In Set-up C, no water droplets are formed, and the cobalt chloride paper remains blue.

Conclusion: This proves that the living plant releases water vapor into the air through transpiration, which condenses into droplets and chemically changes the blue cobalt chloride paper to pink.