Dalton's Law of Partial Pressures (P = P₁ + P₂ + P₃ + further terms)
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P = P₁ + P₂ + P₃ + ...
What each symbol means
| Symbol | What it stands for |
|---|---|
| P | Total pressure of the gas mixture (Pa) |
| Pᵢ | nᵢRT/V = xᵢP where xᵢ = nᵢ/n_total is the mole fraction |
| P₁, P₂, P₃ | Partial pressures of individual gases (Pa) |
When to use this
Valid only for non-reacting ideal gases. Each gas exerts pressure independently as if it alone occupied the entire volume. Partial pressure depends on MOLE fraction, not mass fraction. Pᵢ = xᵢP where xᵢ = nᵢ/Σnⱼ.