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Question One (a) How many degrees of freedom will be present in a solution of sodium sulphate in equilibrium with water vapour? (2) (b) Calculate the density (in kg m?) of paraffin, if a glass capillary of diameter 0.25 mm dipped in paraffin of the surface tension 0.0245 Nm ? rises to a height of 4 cm. The contact angle of paraffin with glass is 28. (4) (c) Use the Kelvin equation to calculate the vapour pressure (in mmHg) of a spherical droplet of water with a diameter of 1.75 x 10-6 cm at 30.0 °C. The vapour pressure of bulk water at that temperature is 31.8 mmHg and its density is 0.998 g cm3. The surface tension of water is 71.18 Dyne cm1 at this temperature. Note: 1 N m1 = 1000 Dyne cm-1 (5) Question Two The figure shows a phase diagram of two components A and B. Describe what happens at point x where the mole fraction of component A is 0.75 as the temperature is decreased until the entire solution is solid. In your explanation indicate what phases are present, their composition and which phase has the greatest number of moles. 250 200 Temperature 150 EM 100 0.0 0.2 0.4 0.6 0.8 1.0 Mole Fraction A (5)