Question

On a bright sunny day, water weeds growing in an aquarium were actively giving off bubbles of gas. Use this information to answer questions that follow:

1. Name the process occurring in the water weed that has resulted in the evolution of these bubbles.
2. Of what gas do these bubbles consist?
3. Briefly describe the reactions occurring in the leaves of the water weeds leading to the evolution of these bubbles.
4. Give an overall balanced chemical equation to represent the process named in (i) above.

Answer 1

1. Photosynthesis.
2. Oxygen.
3. The process that takes place first in the photolysis of water is H+ and OH- ions with the help of energy from sunlight. The hydroxyl ions combine to form hydrogen peroxide 2OH —> H₂O₂ which decompose to give molecular oxygen, i.e.,
   2H₂O₂ ——> 2H₂O + O₂
4. \[\ce{6CO2+12H2O ->[Light][ChlorophyII]C6H12O6+6H2O}\]