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
| Variable | Description | Default |
|---|---|---|
p1 | Initial Pressure (P₁)(atm) | 1 |
v1 | Initial Volume (V₁)(L) | 10 |
t1 | Initial Temperature (T₁)(K) | 300 |
p2 | Final Pressure (P₂)(atm) | 2 |
t2 | Final 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
- 01V₂ = (P₁V₁T₂) / (T₁P₂)
- 02V₂ = (1 × 10 × 350) / (300 × 2)
- 03V₂ = 3500 / 600
- 04V₂ = 5.833 L
Frequently Asked Questions
What laws does the combined gas law combine?
It combines Boyle's law (constant T), Charles's law (constant P), and Gay-Lussac's law (constant V) into one equation.
Does it apply to real gases?
It works well for gases at moderate conditions. At high pressures or low temperatures, use the van der Waals equation.
Must temperature be in Kelvin?
Yes. Using Celsius will give incorrect results because gas laws require absolute temperature.
Ready to run the numbers?
Open Combined Gas Law Calculator