Physics

Van der Waals Equation Calculator

Find real-gas pressure using the van der Waals equation.

Amount (mol)

Temperature (K)

Volume

Constant a (Pa·m⁶/mol²)

Constant b (m³/mol)

Calculated Output

Pressure (Pa) 112,847.46

Formula: P = nRT ÷ (V − nb) − a·n² ÷ V²

Step-by-Step Breakdown

1. Values used:

2. Amount = 1 mol

3. Temperature = 300 K

4. Volume = 0.022

5. Constant a = 0.364 Pa·m⁶/mol²

6. Constant b = 0 m³/mol

8. Pressure = 112,847.46Pa

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The math behind it

P = nRT/(V − nb) − a·n²/V². The 'a' term accounts for attraction, 'b' for molecular volume.

CO₂ (a 0.364, b 4.27×10⁻⁵), 1 mol, 300 K, 0.022 m³ → about 112 kPa.

Where do a and b come from?

They are gas-specific constants found in reference tables.