Question

Calculate the vapor pressure of a solution made by dissolving 94.5 g of urea (molar mass= 60.06 g/mol) in 214.5 mL of water at 35°C (Hint: The vapor pressure of pure water at 35°C is given in the table below. Assume the density of the solution is 1.00 g/mL.) What is the magnitude of vapor-pressure lowering? mmHg

Answer 1

Moles of unea = 94.5% 60.06 g = 1.5734 mole. mole 2 Moles of water = ( 214.5 mLX 19 AL) = 11,9034 mole Moles of Water - = 11,9034 mole. m2 mole More froction of water = moles of water moleswater t moles urea = 11.9034 11.9034 +1.5734 = 0.88325 Now Pressure of solution = mole fraction x Vapor Pressure of water of pure water = 0.88325 x 42.18 mmig [= 37.255 mming Magnitude of Vapor-pressure lowering = 42.18 - 37.255 minHg = 4.925 mmHg