Boiling and the Boiling Point When a liquid is heated in a container open to atmosphere, vapor bubbles form within the bulk of the liquid, rise to the surface throughout the liquid and escape. When the pressure exerted by escaping molecules equals that exerted by the gases of atmosphere, The heat absorbed during boiling is used only to convert liquid molecules to vapor. The temperature at which the vapor pressure of a liquid is equal to Standard atmospheric pressure (1 atm = 760 mmHg) is the normal boiling point. the boiling occurs.

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