At the Boiling point of a liquid,
the vapour pressure of the liquid equals the applied pressure. Bubbles of vapour
which form below the surface of the liquid contain vapour at a pressure which
matches the applied pressure. They are therefore not crushed by the surrounding liquid,
and their bouyancy causes them to rise through
the liquid to the surface to give the familiar appearance of a boiling liquid.
Safety data sheets
quote the "normal" boiling point, which is the temperature at which a liquid boils when
the applied pressure is 1 atmosphere.
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