Step1 Total pressure = partial pressure of Hydrogen + Vapour pressure of water at the given temperature. Step2 Partial pressure of Hydrogen = 767 - Vapour pressure of water at 295.3 K Step3 = 767.0- 20.2 = 746.8 torr Solution Step1 Total pressure = partial pressure of Hydrogen + Vapour pressure of water at the given temperature. Step2 Partial pressure of Hydrogen = 767 - Vapour pressure of water at 295.3 K Step3 = 767.0- 20.2 = 746.8 torr.