Gay Lussac Law
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Gay-Lussac law | p/T = const at fixed V | Gay-Lussac 1802 |
| Isochoric | Constant volume and amount | Ideal gas law |
| Absolute scale | Must use kelvin | Temperature scale |
| Pressure coefficient | β = 1/273.15 K⁻¹ ideal | Gas properties |
| Engineering note | Vessel pressure rises with T | Pressure vessel safety |
| Real deviation | Real gases deviate at high p | Real gas correction |
Constants used on this page and their authoritative sources, for verification and citation
| Constant | Value | Unit | Source |
|---|---|---|---|
| Molar gas constant R | 8.314462618 | J·mol⁻¹·K⁻¹ | New SI (derived from exact N_A·k) |
| Celsius scale zero point T_0 | 273.15 | K | SI / ITS-90 defining value (exact) |
| Volume expansion coefficient of an ideal gas | 1/273.15 = 3.6610e-3 | K⁻¹ | Derived from Gay-Lussac's law and T_0 |
| Standard atmosphere | 101 325 | Pa | ISO 2533 defining value (exact) |
Note: Gay-Lussac's law P₁/T₁ = P₂/T₂ holds only at constant volume with a fixed amount of gas, and temperature must be in kelvin; use a real-gas equation of state at high pressure or near liquefaction.