Enter any five of the six variables — Initial Pressure (P₁), Initial Volume (V₁), Initial Temperature (T₁), Final Pressure (P₂), Final Volume (V₂), and Final Temperature (T₂) — then hit Calculate to solve for the missing one, with P₁V₁/T₁ and P₂V₂/T₂ shown side by side to confirm the relationship holds.
Calculated Result
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P₁V₁/T₁
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P₂V₂/T₂
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The combined gas law formula is P₁V₁/T₁ = P₂V₂/T₂, where P is pressure, V is volume, and T is temperature. It combines Boyle's Law, Charles' Law, and Gay-Lussac's Law into one equation.
To find T₂, rearrange the formula: T₂ = (P₂ × V₂ × T₁) / (P₁ × V₁). Input your initial conditions and final pressure and volume to calculate the final temperature.
Yes, when volume is constant, pressure and temperature are directly proportional (Gay-Lussac's Law). As temperature increases, pressure increases proportionally, assuming the gas behaves ideally.
Use consistent units throughout your calculation. Common combinations include: pressure in atm, volume in L, and temperature in K (Kelvin). Always convert Celsius to Kelvin by adding 273.15.
An isothermal process occurs at constant temperature. In this case, the combined gas law simplifies to Boyle's Law: P₁V₁ = P₂V₂, showing that pressure and volume are inversely proportional.
An isobaric process occurs at constant pressure. The combined gas law simplifies to Charles' Law: V₁/T₁ = V₂/T₂, showing that volume and temperature are directly proportional when pressure remains constant.
The combined gas law applies to ideal gases under normal conditions. It may be less accurate for real gases at very high pressures, very low temperatures, or when intermolecular forces become significant.