理想气体定律Ideal gas law

它综合了玻意耳定律（温度不变时 pV 为常数）、查理定律和盖-吕萨克定律（压强或体积不变时 V 或 p 与 T 成正比）以及阿伏伽德罗定律（同温同压下 V 与 n 成正比）。从气体分子运动论也可推导出这一方程。

It combines Boyle's law (pV constant at fixed temperature), Charles's and Gay-Lussac's laws (V or p proportional to T at fixed pressure or volume) and Avogadro's law (V proportional to n at fixed temperature and pressure). It can also be derived from the kinetic theory of gases.

代入前必须换算为 SI 单位：1 dm³ = 10⁻³ m³，1 cm³ = 10⁻⁶ m³，T(K) = t(°C) + 273。由 n = m/M 可得 M = mRT/(pV)，用来测定挥发性物质的相对分子质量。例：0.50 g 某气体在 100 kPa、298 K 时体积 0.28 dm³，M = 0.50 × 8.314 × 298 ÷ (1.00 × 10⁵ × 2.8 × 10⁻⁴) ≈ 44 g mol⁻¹。

Convert to SI units first: 1 dm³ = 10⁻³ m³, 1 cm³ = 10⁻⁶ m³, T(K) = t(°C) + 273. With n = m/M, M = mRT/(pV), which gives the relative molecular mass of a volatile substance. Example: 0.50 g of a gas occupying 0.28 dm³ at 100 kPa and 298 K has M = 0.50 × 8.314 × 298 ÷ (1.00 × 10⁵ × 2.8 × 10⁻⁴) ≈ 44 g mol⁻¹.

方程严格只适用于理想气体。实际气体在低温、高压时偏离较大，因为分子本身占有体积、分子间存在吸引力；高温、低压下接近理想。

The equation strictly applies only to ideal gases. Real gases deviate at low temperature and high pressure because molecules have volume and attract one another; they approach ideal behaviour at high temperature and low pressure.