Combine Gas Law

Return to Chemistry Index Page

Combine Gas Law is a gas law that represents pressure, volume and temperature relationships on a fixed amount of gas. The Combine Gas Law can written as K=PV/T In the Combine Gas Law the constant depends on the amount of gas present. The formula for the Combine Gas Law is

P₁V₁  /T₁=P₂ V₂/T₂ The temperature used to solve the Combine Gas Law should be in Kelvin. The formula for Kelvin is K= C + 273.15.

Example Problem:

A helium balloon has a volume of 35 L at 20 K and 3 atm. What volume will the balloon have at 15 K and 2 atm?

P₁= 3 atm

T₁= 20 K

V₁₌  35 L

P₂= 2 atm

T₂= 15 K

V₂₌ ?

You take the Combine Gas Law P₁V_{1 /}T₁=P₂ V_2/T₂ and rearrange the variables to fit the new formula for the variable that needs to be solved.

P₁V_{1 /}T₁=P₂ V_2/T₂

P₁V₁ T₂=P₂ V₂T₁

V₂= P₁V₁ T_{2 /} P₂ T₁

V₂= (3) atm (35 L) (15 K) / (2 atm) (20 K)

V₂= 39.38 L