Physics – 2.1.2 Particle model | e-Consult

If the volume of a gas is increased while the number of moles and temperature are kept constant, the pressure of the gas will decrease. This is because increasing the volume gives the gas particles more space to move. With more space, the particles collide with the container walls less frequently. Since pressure is force per unit area, fewer collisions mean a lower total force on the walls, resulting in lower pressure.

If the number of moles of a gas is increased while the volume and temperature are kept constant, the pressure of the gas will increase. Increasing the number of moles means there are more gas particles in the container. With more particles, there are more collisions with the container walls. More collisions mean a greater total force exerted on the walls, leading to higher pressure. The increased number of particles increases the frequency of collisions, directly increasing the pressure.

The following table summarizes these relationships: