What Is The Formula For The Combined Gas Law?

Relating Pressure, Volume, and Temperature of a Gas

The combined gas law accounts for pressure, volume, and temperature.
The combined gas law accounts for pressure, volume, and temperature. Paul Taylor, Getty Images

Question: What Is The Formula For The Combined Gas Law?

The combined gas law examines the behavior of a constant amount of gas when pressure, volume and/or temperature is allowed to change.

Answer: The combined gas law is expressed as:

PiVi/Ti = PfVf/Tf

where Pi = initial pressure
Vi = initial volume
Ti = initial absolute temperature
Pf = final pressure
Vf = final volume
Tf = final absolute temperature

It is extremely important to remember the temperatures are absolute temperatures measured in Kelvin, NOT °C or °F.



It is also important to keep your units constant. Do not use pounds per square inch for pressures initially to find Pascals in the final solution.