Gay-Lussac's Law Calculator
Use Gay-Lussac's law to find the new pressure of a gas when its temperature changes at constant volume.
How it works
P₁ / T₁ = P₂ / T₂ · P₂ = P₁ × T₂ / T₁ (constant volume, T in kelvin)
Gay-Lussac's law states that at constant volume the pressure of a fixed amount of gas is directly proportional to its absolute temperature. Heat a sealed rigid container and the molecules strike the walls harder and more often, so the pressure climbs in step with the kelvin temperature. The ratio P/T stays constant.
Worked example
A gas at 1 atm and 300 K heated to 350 K in a rigid vessel reaches P₂ = 1 × 350 ÷ 300 ≈ 1.167 atm.
Sources: Gay-Lussac's law — Wikipedia
Frequently asked questions
What is held constant?
Volume and the amount of gas. Gay-Lussac's law isolates the pressure–temperature relationship, which is why it applies to sealed rigid containers like aerosol cans.
Why do pressurised cans warn against heat?
Because pressure rises with temperature at fixed volume. Enough heating can push the internal pressure past what the can can hold, causing it to burst.
Does the pressure unit matter?
No, as long as it is consistent on both sides — the units cancel in the ratio. Temperature, however, must be absolute (kelvin).
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