Anhydrous calcium chloride is often used as a dessicant. In the presence of excess of CaCl2, the amount of the water taken up is governed by Kp=6.4×1085 for the following reaction at room temperature, CaCl2(s)+6H2O(g)⇌CaCl2.6H2O(s). What is the equilibrium vapour pressure of water in a closed vessel that contains CaCl2(s)?