Answer
(a) The normal boiling point of a liquid is the temperature at which the vapour pressure of the liquid is equal to one atmosphere pressure (760 mm of Hg or 760 torr).
(b) The boiling point of a liquid is the temperature at which its vapour pressure equals the pressure of the gas above it. Thus, the atmospheric pressure over the liquid must be specified when measuring its boiling point.
Work Step by Step
(a) The normal boiling point of a liquid is the temperature at which the vapour pressure of the liquid is equal to one atmosphere pressure (760 mm of Hg or 760 torr).
(b) The boiling point of a liquid is the temperature at which its vapour pressure equals the pressure of the gas above it. Thus, the atmospheric pressure over the liquid must be specified when measuring its boiling point. An increase in pressure of the gas above the liquid (applied pressure) leads to an increase in the boiling point of the liquid, and a decrease in the applied pressure results in a decrease in the boiling point of the liquid.
