Combined Gas Law and its Constituent Laws

This is the equation for the combined gas law: 

P₁V₁/T₁ = P₂V₂/T₂

• P: Pressure of Gas

• V: Volume of Gas (L)

• T: Temperature of Gas (K)

Its use: To compare and determine values of a sample of gas under two different sets of conditions. 

Constituent Laws of The Combined Gas Law

Here is a dissection of the combined gas law. If one value of the combined gas law stays constant between two separate sets of conditions for a sample of gas, these three laws can be used instead. 

Boyle's Law

• P₁V₁ = P₂V₂

• Inverse relationship between P and V of a gas sample when T is constant. 

  • Decreasing volume increases the pressure due to compression, resulting in more particle collisions. 

Charles's Law

• V₁/T₁ = V₂/T₂

• Direct relationship between V and T of a gas sample when P is constant. 

  • Increasing temperature increases volume due to more kinetic energy, resulting in expansion. 

Gay-Lussac's Law

• P₁/T₁ = P₂/T₂ 

• Direct relationship between P and T of a gas sample when V is constant. 

  • Increasing temperature increases pressure due to more particle collisions.