Question

Liquid water is about 800 times denser than dry air under standard conditions. Use kinetic molecular theory to explain this difference in the densities of the two substances.

Answer 1

Kinetic molecular Theory points:

1. Gases molecules are always in random motion.

2. Gases molecule collide with each other and with the walls of container.

3.  Gases molecules total volume is negligible as compare to container.

4. There is no attractive forces between the gases particles

5. K.E is directly proportional to absolute temperature.

Why liquid are denser than gases according to K.M.T:

1. As gases are in random motion, so they have weak forces/ no attractive forces (Acc. to KMT) due to this they are apart as compare to liquid which have stronger forces are closer to each other. So volume of gases will be greater. d= m/v

2.  K. E of gases are greater than liquid due to this gases move randomly, apart from each another. Due to this their volume will be greater. d= m/v

3. Gases molecules total volume is negligible as compare to container which show that gases molecules have large spaces between them which causes lower in density.