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Mathematics

Gas Law Calculator

Ideal Gas Law Calculator (PV = nRT)

What is Gas Law Calculator?

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Gas law calculators solve Boyle's, Charles's, Gay-Lussac's, and the combined gas law for pressure, volume, and temperature relationships of ideal gases.

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Formula

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f(x)PV = nRT (ideal gas law); P₁V₁/T₁ = P₂V₂/T₂ (combined gas law)

Variable Legend

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SymbolNameUnitDescription
PPressureatm/Pa—
VVolumelitres/m³—
nMoles of gasmol—
RGas constant0.0821 L·atm/(mol·K)—
TTemperatureKelvin—

How to Gas Law Calculator

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  1. 1Boyle's law: P₁V₁ = P₂V₂ (constant T)
  2. 2Charles's law: V₁/T₁ = V₂/T₂ (constant P)
  3. 3Gay-Lussac's: P₁/T₁ = P₂/T₂ (constant V)
  4. 4Combined: P₁V₁/T₁ = P₂V₂/T₂

Worked Examples

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Example 1
Given:Boyle's: V₁=4L, P₁=2atm, P₂=4atm
Result:V₂ = P₁V₁/P₂ = 2×4/4 = 2L

Real-World Applications

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Chemistry laboratory calculations

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Scuba diving safety (decompression)

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HVAC system design

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Industrial gas processing

Gas Law Summary

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LawConstantEquation
Boyle'sTemperatureP₁V₁=P₂V₂
Charles'sPressureV₁/T₁=V₂/T₂
Gay-Lussac'sVolumeP₁/T₁=P₂/T₂
CombinedAmountP₁V₁/T₁=P₂V₂/T₂
Ideal gas—PV=nRT

Frequently Asked Questions

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Q

When should I use ideal gas law vs combined?

A

Ideal: when n (moles) is constant or unknown. Combined: when gas amount is fixed, conditions change.

Q

What temperature units should I use?

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Always Kelvin (K = °C + 273.15) in gas law equations. Celsius and Fahrenheit don't work.

Q

Is the ideal gas approximation accurate?

A

Good for most gases at normal conditions. Poor at high pressure or low temperature. Use van der Waals for precision.

Mathematically verified
Reviewed October 2026
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