Calcolatore Variazione di Entalpia
Calcola la variazione di entalpia di una reazione chimica.
Pressure (Van der Waals)
24.0666 atm
Pressure (Van der Waals) vs Moles of Gas (n)
Formula
Van der Waals Equation
Formula
[P + a(n/V)²] × [V - nb] = nRT
Solving for P: P = nRT/(V - nb) − a(n/V)²
Where:
The a term reduces pressure (attraction pulls molecules inward). The b term reduces available volume.
Esempio Risolto
1 mol of N₂ (a = 1.36, b = 0.0318) at 300 K in 1 L.
- 01P = nRT/(V - nb) - a(n/V)²
- 02P = (1)(0.08206)(300)/(1 - 1×0.0318) - 1.36(1/1)²
- 03P = 24.618/0.9682 - 1.36
- 04P = 25.42 - 1.36
- 05P = 24.06 atm
Domande Frequenti
What do the Van der Waals constants represent?
The constant a accounts for attractive forces between molecules (larger a = stronger attractions). The constant b accounts for the finite volume of molecules (larger b = bigger molecules).
Where do I find a and b values?
They are tabulated for common gases. For example, CO₂: a = 3.59, b = 0.0427; H₂O: a = 5.46, b = 0.0305.
When is the Van der Waals equation needed?
Use it at high pressures (above ~10 atm) or low temperatures where intermolecular forces become significant and ideal gas behavior breaks down.
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