## 2008-07-16

### Boyle's Law

Boyle's Law can be explained by using the kinetic theory of gases.

When the volume of a gas in a container of gas molecules is reduced.

a) its density increased, that is, the number of gas molecules per unit volume increases.
b) the surface area of the container decreases.

The end result is that, the number of gas molecules which hit onto a surface area of the container per unit area also increases.

The increase in this rate of change of momentum in turn causes the pressure of the gas to increase.

If the volume of the container is otherwise increased:

a) density of the gas decreases, the number of gas molecules per unit volume increases.
b) the surface area of the container increases.

Therefore, the number of gas molecules hitting a unit surface area per unit time decreases.

The pressure is thus decreased.

BOYLE'S LAW states that for a fixed mass of gas at a fixed temperature, the pressure of the gas is inversely proportional to its volume.

According to Boyle's Law

P1V1 = P2V2

P1 = initial pressure
V1 = initial volume
P2 = final pressure
V2 = final volume