Molecular Origin of Gas Pressure

Consider gas molecules moving inside a container. When a molecule strikes a wall, its momentum component perpendicular to that wall changes. A momentum change requires an impulse. Therefore the molecule exerts a force on the wall. One collision produces only a tiny force. But an enormous number of collisions occur every second. The average result is a measurable force. Pressure is: p = FA where `F` is the average normal force on wall area `A`. Higher temperature generally means greater average translational kinetic energy. Molecules then collide with the walls more energetically. At fixed volume and molecule number, this contributes to larger pressure.

**p = FA Microscopically: pressure ↔ rate of momentum transfer per unit area**