Charles Law for Behavior of Gases

Fluid Flow Table of Contents
Hydraulic and Pneumatic Knowledge

Charles Law for Behavior of Gases

Charles' Law, or the law of volumes, says that, for a given mass of an ideal gas at constant pressure, the volume is directly proportional to its absolute temperature , asuming a closed system.

As a mathematical equation, Charles' law is written as:

T₁V₂ - T₂V₁  or T₁P₂ = T₂P₁

T₁, P₁ and V₁ are initial temperature, pressure, and volume, and T₂, P₂, and V₂ are final conditions

Increasing the temperature of a volume of gas causes individual gas molecules to move faster. As the molecules move faster, they encounter the walls of the container more often and with more force. In an inflexible container, the more frequent and forceful collisions result in higher pressure. However, if the container volume is adjustable, the volume will increase, and the pressure will remain the same. Charles' Law is the formal description of this relationship, allowing change in volume to be calculated if the temperature change is known.