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Ideal gas law calculator

Solve the ideal gas law PV = nRT for pressure, volume, moles or temperature in any units, or find a new state with the combined gas law.

更新日 検証済みの例：6

試す
体積
L
体積: 22.414 L
有効桁数：6；最も近い値へ、等距離ならゼロから遠い値へ
圧力
101.325kPa / 1atm
Amount of gas
1mol
温度
273.15K / 0°C
Molar volume V/n
22.414L/mol
Number of molecules
6.02214 × 10²³

1 mol of ideal gas at 273.15 K (0 °C) and 101.325 kPa occupies 22.414 L — 22.414 L per mole.

Isotherm through this state (P–V)

01002003004000204060Volume (L)Pressure (kPa)101.3 kPa, 22.41 L
計算方法 S

  1. Convert to SI units

    P=101,325 Pa, V=0.022414 m3, n=1 mol, T=273.15 KP = 101{,}325\ \mathrm{Pa},\ V = 0.022414\ \mathrm{m^3},\ n = 1\ \mathrm{mol},\ T = 273.15\ \mathrm{K}

    Temperature is always absolute in gas laws: K = °C + 273.15.

  2. Solve PV = nRT for V

    V=nRTP=(1)(8.314462618)(273.15)101,325=0.022414 m3=22.414 LV = \frac{nRT}{P} = \frac{(1)(8.314462618)(273.15)}{101{,}325} = 0.022414\ \mathrm{m^3} = 22.414\ \mathrm{L}

Ideal gas law calculatorについて

The ideal gas law, PV = nRT, links the pressure, volume, amount and absolute temperature of a gas through the molar gas constant R = 8.314 462 618… J/(mol·K). Choose the unknown and enter the other three in any units; the calculator converts to pascals, cubic metres, moles and kelvin before solving. The combined gas law mode holds the amount fixed and uses P₁V₁/T₁ = P₂V₂/T₂ to find a new pressure, volume or temperature.

Students use it to find the volume of gas a reaction gives off, and engineers use it to estimate how much gas a tank holds. With the defaults, 1 mol at 0 °C and 1 atm occupies 22.414 L, the CODATA molar volume of an ideal gas at those conditions.

The law ignores molecular size and attraction. Carbon dioxide at 25 °C and 1 atm deviates from it by about 0.5 %; the calculator warns above 100 bar or below 150 K, where a van der Waals or virial equation fits better.

計算例

1 mol at 0 °C and 1 atm

Law
PV = nRT
Solve for
体積
Pressure P
1 atm
Amount of gas n
1
Amount unit
mol
Temperature T
0 °C
体積
22.414 L

照合元：CODATA 2022 molar volume of an ideal gas at 273.15 K, 101.325 kPa: 22.413 969 54 L/mol

Pressure of 2 mol in 10 L at 300 K

Law
PV = nRT
Solve for
圧力
Volume V
10 L
Amount of gas n
2
Amount unit
mol
Temperature T
300 K
圧力
498.868 kPa

照合元：Python 3.8 decimal: 2 × 8.31446261815324 × 300 / 0.01 = 498867.757 Pa

Moles in 1 m³ at 100 kPa and 25 °C

Law
PV = nRT
Solve for
Amount
Pressure P
100 kPa
Volume V
1 m³
Temperature T
25 °C
Amount of gas
40.3395 mol

照合元：Python 3.8 decimal: 100000 / (8.31446261815324 × 298.15) = 40.3395455

Temperature of 1 mol in 24.465 L at 1 atm

Law
PV = nRT
Solve for
温度
Pressure P
1 atm
Volume V
24.465 L
Amount of gas n
1
Amount unit
mol
温度
298.145 K

照合元：Python 3.8 decimal: 101325 × 0.024465 / 8.31446261815324 = 298.14508 K

よくある質問

What is the value of R in PV = nRT?

R = 8.314 462 618 153 24 J/(mol·K), exact since the 2019 SI revision because it is the product of two fixed constants, the Avogadro constant and the Boltzmann constant. In other units it is 0.082 057 L·atm/(mol·K), 8.314 L·kPa/(mol·K) and 62.364 L·mmHg/(mol·K). Use the version that matches your pressure and volume units, or convert everything to SI as this calculator does.

What volume does one mole of gas occupy at STP?

It depends on which STP is meant. At 0 °C and 1 atm (101.325 kPa), one mole of ideal gas occupies 22.414 L; at 0 °C and 100 kPa, the standard pressure IUPAC has recommended since 1982, it occupies 22.711 L; at 25 °C and 1 atm it occupies 24.465 L. Check which definition your textbook or exam uses, since the first two differ by 1.3 %.

Why does temperature have to be in kelvin?

Gas pressure and volume are proportional to absolute temperature, which starts at absolute zero, −273.15 °C. Going from 10 °C to 20 °C looks like doubling, but the absolute temperature only rises from 283.15 K to 293.15 K, a 3.5 % increase, so at constant pressure the gas expands by 3.5 %, not 100 %. The calculator converts °C and °F to kelvin before solving.

What is the combined gas law?

P₁V₁/T₁ = P₂V₂/T₂ for a fixed amount of gas. It merges Boyle's law (PV constant at fixed temperature), Charles's law (V/T constant at fixed pressure) and Gay-Lussac's law (P/T constant at fixed volume). Heating a sealed rigid container from 20 °C to 40 °C raises 100 kPa to 106.8 kPa, because the pressure scales with 313.15 K ÷ 293.15 K.

「Ideal gas law calculator」の精度はどのくらいですか？

精度は入力値と計算方法の前提に依存します。十進演算には有効数字50桁を使いますが、推定、数値計算手法、元データの精度はそれより低い場合があります。表示の丸め処理でこれらの制約がなくなるわけではありません。 独立した出典の解答と照合した計算例：6。 例えば、「1 mol at 0 °C and 1 atm」はCODATA 2022 molar volume of an ideal gas at 273.15 K, 101.325 kPa: 22.413 969 54 L/molと照合しています。

この計算方法の出典は何ですか？

CODATA 2022 — molar gas constant R and molar volume of an ideal gas (22.413 969 54 L/mol at 273.15 K, 101.325 kPa); OpenStax Chemistry 2e, §9.2 Relating pressure, volume, amount, and temperature: the ideal gas law.

この計算機について

PV=nRT, R=8.314 462 618… J mol−1 K−1 (exact);P1V1T1=P2V2T2PV = nRT,\ R = 8.314\,462\,618\ldots\ \mathrm{J\,mol^{-1}\,K^{-1}}\ (\text{exact});\qquad \frac{P_1V_1}{T_1} = \frac{P_2V_2}{T_2}

出典

  1. CODATA 2022 — molar gas constant R and molar volume of an ideal gas (22.413 969 54 L/mol at 273.15 K, 101.325 kPa)
  2. OpenStax Chemistry 2e, §9.2 Relating pressure, volume, amount, and temperature: the ideal gas law

出典と照合済み

この計算機には、独立した出典の解答を使った計算例が 6 件あります。テストに組み込まれており、ここでも実行できます。

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