Ideal Gas Law Calculator

Solve PV = nRT for any variable: pressure, volume, moles, or temperature.

🌡️ Ideal Gas Law – PV = nRT

Solve For:

P – Pressure atm

V – Volume L

n – Moles mol

T – Temperature K

R = 0.08206 L·atm/mol·K | R = 8.314 J/mol·K

⚠ Please enter valid positive values for all three known variables.

Ideal Gas Law

PV = nRT

Result

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🌡️ Ideal Gas Law Formula Explained

The Ideal Gas Law combines three simpler gas laws into one powerful equation:

PV = nRT

P = Pressure (atm, kPa, Pa, mmHg)
V = Volume (L, mL, m³)
n = Amount of gas (moles)
R = Universal gas constant = 0.08206 L·atm/mol·K
T = Absolute temperature (Kelvin)

Derived Gas Laws

Boyle's Law (T,n = const)

P₁V₁ = P₂V₂

Charles Law (P,n = const)

V₁/T₁ = V₂/T₂

Gay-Lussac (V,n = const)

P₁/T₁ = P₂/T₂

STP Conditions

0°C, 1 atm → 22.4 L/mol

📖 Step-by-Step Example

✅ Find Volume at STP

Given: 2 mol gas at P = 1 atm, T = 273.15 K (0°C)

Step 1: V = nRT / P

Step 2: V = (2 × 0.08206 × 273.15) / 1

Step 3: V = 44.8 / 1 = 44.8 L

✅ Find Pressure

Given: n = 0.5 mol, V = 10 L, T = 300 K

Step 1: P = nRT / V

Step 2: P = (0.5 × 0.08206 × 300) / 10

Step 3: P = 12.309 / 10 = 1.231 atm

❓ Frequently Asked Questions

What is the Ideal Gas Law?

The Ideal Gas Law (PV = nRT) describes the state of a hypothetical ideal gas. It's a combination of Boyle's Law, Charles's Law, and Avogadro's Law. It works well for real gases at low pressure and high temperature.

Why must temperature be in Kelvin?

Kelvin is the absolute temperature scale with a true zero at absolute zero (−273.15°C). Using Celsius or Fahrenheit would give incorrect results because the gas law requires absolute temperature. Convert: K = °C + 273.15

What is the value of R?

R = 0.08206 L·atm/mol·K when using atmospheres and litres. R = 8.314 J/mol·K when using pascals and cubic metres. Always match units consistently.

What is STP?

STP (Standard Temperature and Pressure) is defined as 0°C (273.15 K) and 1 atm. At STP, 1 mole of an ideal gas occupies 22.4 litres.

When does the ideal gas law fail?

The ideal gas law fails at very high pressures or very low temperatures, where intermolecular forces and molecular volumes become significant. In these cases, use the van der Waals equation instead.

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Comprehensive Guide

The Science Behind Ideal Gas Law

Leverage this Ideal Gas Law Calculator to instantly determine exact values without the hassle of manual formula manipulation. A solid grasp of Ideal Gas Law is critical for safely and effectively handling chemical compounds in practical scenarios. Mastering the concepts behind Ideal Gas Law is crucial for understanding advanced chemical reactions and laboratory procedures.

Why is Ideal Gas Law Important?

In analytical chemistry, precision is everything. Having a reliable way to compute Ideal Gas Law saves time, prevents wasted materials, and ensures scientific accuracy.

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Speed

Instant

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Accuracy

100%

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Level

All Levels

Always verify your input units before calculating. Mismatched units (e.g., using mL instead of L) are the most common source of error when determining Ideal Gas Law!

Common Applications

Academic Study: Checking literature values against experimental yields.
Laboratory Practice: Calculating theoretical thresholds for experiments.
Data Validation: Improving general chemistry proficiency.

Relying solely on the calculator without understanding the underlying formula. Always review the step-by-step breakdown to internalize the mechanics.