Combined Gas Law Calculator Formula

Understand the math behind the combined gas law calculator. Each variable explained with a worked example.

Formulas Used

Final Volume (V₂)

v2 = (p1 * v1 * t2) / (t1 * p2)

Variables

VariableDescriptionDefault
p1Initial Pressure (P₁)(atm)1
v1Initial Volume (V₁)(L)10
t1Initial Temperature (T₁)(K)300
p2Final Pressure (P₂)(atm)2
t2Final Temperature (T₂)(K)350

How It Works

Combined Gas Law

Formula

P₁V₁ / T₁ = P₂V₂ / T₂

Solving for V₂: V₂ = (P₁V₁T₂) / (T₁P₂)

This combines Boyle's law (P ∝ 1/V), Charles's law (V ∝ T), and Gay-Lussac's law (P ∝ T) into one equation for a fixed amount of gas.

Worked Example

A gas at 1 atm, 10 L, 300 K is compressed to 2 atm and heated to 350 K.

p1 = 1v1 = 10t1 = 300p2 = 2t2 = 350
  1. 01V₂ = (P₁V₁T₂) / (T₁P₂)
  2. 02V₂ = (1 × 10 × 350) / (300 × 2)
  3. 03V₂ = 3500 / 600
  4. 04V₂ = 5.833 L

Ready to run the numbers?

Open Combined Gas Law Calculator