Question

(i) What is meant by 'diffusion'? Give one example of diffusion in gases.
(ii) Why do gases diffuse very fast?
​(iii) Name two gases of air which dissolve in water by diffusion. What is the importance of this process in nature?

Answer 1

(i) Diffusion: The spreading out and mixing of a substance with another substance due to the motion of its particle is called diffusion.
For eg. When food is cooked some of the substance in food release gases having the smell of food in them. These gases move very quickly and mix up with air by diffusion when these gases reach our nose we get the smell of food cooking in the kitchen.

(ii) Diffusion is the mixing of particles of one substance with others. The molecules in gases are far apart from each other due to negligible forces of attraction between them. Thus, gases have very low densities, therefore, they have a maximum rate of diffusion among solids, liquids, and gases.

(iii) The two gases of air which dissolve in water by diffusion are oxygen and carbon dioxide.
1. Carbon dioxide dissolves in water. Fizzy drinks contain carbon dioxide dissolved in water. In nature, this process helps to regulate the world's carbon dioxide supplies as the gas dissolves in water.
2. Oxygen also dissolves in water. It is this dissolved oxygen that makes the aqueous life to breathe.