How does the pressure of an enclosed gas in a rigid container change when the gas is heated? Explain why this change occurs.

Question

aaronq · Answer

Pressure is caused by collisions of particles with a surface - the collisions exert a force on on a given area. 

 $\sf Pressure=\dfrac{Force}{Area}$

Applying heat to a substance increases the movement of the material at the microscopic level, that is particles start vibrating, rotating and translating (moving across space) faster and faster. In other words, the thermal energy applied imparts kinetic energy to the material. Now, particles move faster and faster and collide with the surfaces (in this case, the inner walls of a container) more forcefully resulting in a higher pressure.