# Boiling point and vapor pressure

Does a liquid having higher vapor pressure have a lower boiling point? I think so because I read in wikipedia that, "A substance with a high vapor pressure at normal temperatures is often referred to as volatile." A volatile liquid has lower boiling point.

• Do you know the definition of "boiling point"? – SendersReagent Feb 26 '16 at 4:43
• Temperature at which vapour pressure is equal to the external pressure. – chem007 Feb 26 '16 at 5:56
• So would a compound with a higher bp or lower bp reach this first? – SendersReagent Feb 26 '16 at 13:17
• consider two substance A and B.If A has more vapour pressure than B then you can think it as,A has more particles in vapour phase than that B has in the vapour phase.Which means A will attain a vapour pressure which is equal to external pressure more quickly than B.Since A and B are same temperature (say 356K) and since A attains a vapour pressure equal to external pressure more quickly than B =>(implies) A boils quicker than B which implies A has lower boiling point than B. – Abhishek Pallippara gopakumar Feb 28 '16 at 17:10

Not necessarily. The vapor pressure of a liquid (or solid) is the pressure of the vapor in equilibrium with its condensed phase in a closed system. The boiling point of a liquid at a given pressure is the temperature at which the vapor pressure is equal to the given pressure. This means the vapor pressure is a function of the temperature, $P^* = f(T)$, and the boiling point is a function of the pressure, $T_{bp} = f(P)$.