van der Waals Equation Calculator
Compare the pressure of a real gas (using van der Waals parameters a and b) with the ideal gas law.
Calculation Parameters
Adjust the values below.
Calculated Result
Expert Tip
Ensure units are correctly formatted (e.g. Kelvin for gas temperatures and liters for volumes) to get chemically accurate outputs.
How this Calculator Works
This calculator allows you to solve van der Waals Equation problems dynamically. Adjust the input parameters using the sliders or selection menu below:
- Temperature (T, °C) (Range: -50 to 500, Default: 25)
- Volume (V, L) (Range: 0.5 to 50.0, Default: 2.0)
- Moles (n, mol) (Range: 0.1 to 10.0, Default: 1.0)
- van der Waals Constant a (L²·atm/mol²) (Range: 0.0 to 10.0, Default: 3.59)
- van der Waals Constant b (L/mol) (Range: 0.010 to 0.150, Default: 0.0427)
The results are computed instantly and updated in the results panel on the right.
Formula & Methodology
where a represents molecular attraction forces and b represents molecular size exclusion.
Where:
- Temperature: Parameter value.
- Volume: Parameter value.
- Moles: Parameter value.
- van der Waals Constant a: Parameter value.
- van der Waals Constant b: Parameter value.
Step-by-Step Calculation Example
To calculate van der Waals Equation manually, follow these steps:
- Identify the input parameters. For example:
- Temperature (T, °C) = 25
- Volume (V, L) = 2.0
- Moles (n, mol) = 1.0
- van der Waals Constant a (L²·atm/mol²) = 3.59
- van der Waals Constant b (L/mol) = 0.0427
- Apply the formula:
P = (n * R * T) / (V - n * b) - a * (n/V)^2
where a represents molecular attraction forces and b represents molecular size exclusion. - Verify the calculated value which is updated instantly in the results panel on the right.
Frequently Asked Questions
What is the van der Waals equation for real gases? ▼
(P + a × (n/V)²) × (V - n × b) = n × R × T.
What do van der Waals constants a and b represent? ▼
Constant 'a' corrects for intermolecular attractive forces; constant 'b' corrects for finite volume occupied by gas molecules.
When does the van der Waals equation reduce to the ideal gas law? ▼
At low pressures and high temperatures where molecular volume and attractive forces become negligible (a → 0, b → 0).