Question

Water is evaporating into initially dry air in the closed cylindrical vessel. The inside diameter of the vessel is 10 cm and the height is 20 cm. The vessel is isothermal at 25^oC and the vapor pressure of water is 23.8 mmHg. This vessel has 500 cm³ of water. The rate of transfer of water from the liquid to the gas per unit area of gas-liquid interface is given by the expression rw(mol/cm2.s) = k(C*w - Cw) where

Cw(mol/cm3) = actual concentration of water vapor in the air.

C*w(mol/cm3) = concentration of water vapor in the air that would be in equilibrium with the liquid phase.

If k = 0.034 cm/sec how long will it take for the air to reach 90% saturation (equilibrium)?

Answer 1