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: - **a** = correction for intermolecular attraction (L²·atm/mol²) - **b** = correction for molecular volume (L/mol) - Other variables as in the ideal gas law 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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