Name: Diffusion in Plants and Humans
Uploaded: 2019-07-19
Duration: 3 min 43 s
Description: Diffusion is important for gaseous exchange in plants and various body functions in humans. Learn in this video how diffusion is important to organisms.

Question

How would you show that exhaled air has carbon dioxide?

Accepted Answer

Exhaled air has carbon dioxide, we can show this by following activity:

Experiment: Stir a couple of spoons of lime in a glass of water. Allow the mixture to settle and decant the clear liquid into two small glasses. Make circular covers for the glasses, using stiff paper. Pierce two holes in each, and insert straws into them. Tape the covers to the glasses. Breathe in through straw B and out through straw C (breathe through your mouth).

Observation: Atmospheric air will enter through A, mix with the limewater in the first glass and enter your mouth through B. On the other hand, the air you exhale will enter the second glass through C. Soon, the limewater in the second glass will turn milky, but that in the first glass will not.

Conclusion: This is because the air you exhale contains carbon dioxide, which turns lime water milky. The carbon dioxide in our exhaled air reacts with the calcium hydroxide in the lime water to produce calcium carbonate which is milky. Atmospheric air also contains this gas, but not enough to turn limewater milky.

How would you show that exhaled air has carbon dioxide?

Important Questions on Respiration in Plants and Animals

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