Pressure and Boiling

Definition

The external weight pressing on a liquid surface that sets the price of phase change. Higher pressure forces molecules to reach higher temperatures before they can escape into vapor.

When a molecule escapes into vapor it must expand into vastly more space and push back everything above the surface, so a heavier load means a harder escape. Pressure does not change how much energy molecules have, it changes how much they need. High pressure from pumps, compressors, or confined steam raises the boiling point, while low pressure from vacuums or condensation lowers it.

Related concepts

Phase Change · Boiler · Latent Heat of Vaporization

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Part of The Blueprint of Water · 🔥 thermodynamics