Pressure
P = nRT / VLoading page content...
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Calculate using PV = nRT
R = 8.314 J/(mol·K)
Enter values above to see results.
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Physical Chemistry Foundation
Solve for pressure, volume, temperature, or moles in ideal gas systems for process screening and education.
Core Law
PV = nRT
Gas Constant R
8.314 J/(mol·K)
Temperature
Kelvin required
Pressure
Absolute only
Reviewed by: CalculatorApp Chemistry & Engineering Team
PV = nRT combines Boyle's, Charles's, and Avogadro's gas laws into a single equation modeling the behavior of gases under a wide range of practical conditions. Engineers and chemists use it for process vessel sizing, pneumatic system design, and lab calculations where high accuracy close to phase transitions is not required.
Pressure
P = nRT / VVolume
V = nRT / PTemperature
T = PV / nRMoles
n = PV / RT| Gas Type | Ideal Gas Accuracy | Typical Use |
|---|---|---|
| Diatomic (N₂, O₂, H₂) | High at normal conditions | Pneumatics, air storage |
| Noble gases (Ar, He) | Very high | Lab reference, shielding gas |
| CO₂ | Moderate | Carbonation, fire suppression |
| Steam / near-critical | Low | Use steam tables for accuracy |
1662: Boyle establishes pressure-volume inverse relationship.
1787: Charles derives volume-temperature proportionality.
1802: Gay-Lussac formalizes pressure-temperature relationship.
1811: Avogadro proposes equal volumes contain equal moles.
1834: Clapeyron unifies these laws into PV = nRT.
1873: Van der Waals introduces real gas corrections.
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Myth: Celsius temperature can be used directly.
Fact: Absolute Kelvin temperature is always required in PV = nRT.
Myth: Gauge pressure is acceptable in the formula.
Fact: Absolute pressure (gauge + atmospheric) must be used.
Myth: Ideal gas works for all industrial gases.
Fact: High-pressure and condensable gases need real gas corrections.
Myth: Ideal gas law works identically for all conditions.
Fact: Accuracy decreases near phase transition or extreme pressures.
PV = nRT relates pressure, volume, moles, and temperature for ideal gases under reasonable conditions.
R is the universal gas constant: 8.314 J/(mol·K). It relates macroscopic and molecular gas behavior.
It works well at low pressures and high temperatures where intermolecular forces and molecular volume are negligible.
At high pressures or near condensation points, real gas equations like van der Waals are more accurate.
Always use absolute temperature (Kelvin). Add 273.15 to Celsius values before using in PV = nRT.
At standard temperature (0°C) and pressure (101.325 kPa), one mole of an ideal gas occupies 22.414 L.
Yes. Dalton's Law allows the ideal gas law to apply to mixtures using partial pressures.
Divide mass by molar mass of the compound (n = m / M) to get moles before using this calculator.
Gas storage sizing, pneumatics, chemical process design, and HVAC volume calculations.
Pressure and volume are highly sensitive to temperature changes; always verify temperature assumptions.
No. Always use absolute pressure (add atmospheric pressure to gauge readings).
No. Use steam tables or real gas equations for high-accuracy work near critical points.
Combine gas calculations with molar mass, molarity, and thermal tools for complete process analysis.
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