Vapour pressure:- At a particular temperature, pressure exerted by vapour on the walls of the container when water and vapour are in equilibrium, is known as vapour pressure.
H2O (water) ➝ H2O (vapour)
Rate of condensation of liquid is directly proportional to concentration of molecules in vapour state. Here, liquid and vapour are in equilibrium. When the temperature of liquid is increased, the number of molecules with higher kinetic energy increases and enter into vapour phase, hence, with increase in temperature, vapour pressure of liquid increases. The temperature at which vapour pressure of liquid becomes equal to the atmospheric pressure is called boiling temperature at that pressure.
