Cyclohexanol, C H,,OH, is sometimes used as the solvent in molecular weight determinations by freezing-point depression. If 0.253 g of benzoic acid, C H COOH, dissolved in 12.45 g of cyclohexanol lowered the freezing-point of pure cyclohexanol by 6.55°C, what is the molal freezing-point constant, Ke, of this solvent? 3.

The vapor pressures of several solutions of water-propanol (CH3CH2CH2OH) were determined at various compositions, with the following data collected at 45C: H2O Vapor pressure(torr) 0 74.0 0.15 77.3 0.37 80.2 0.54 81.6 0.69 80.6 0.83 78.2 1.00 71.9 a. Are solutions of water and propanol ideal? Explain. b. Predict the sign of Hsoln for water-propanol solutions. c. Are the interactive forces between propanol and water molecules weaker than, stronger than, or equal to the interactive forces between the pure substances? Explain. d. Which of the solutions in the data would have the lowest normal boiling point?

A 1.00 mol/kg aqueous sulfuric acid solution, H2SO4,freezes at 4.04 C. Calculate i, the vant Hoff factor,for sulfuric acid in this solution.

The dispersed phase of a certain colloidal dispersion consists of spheres of diameter 1.0 102 nm. (a) What are the volume (V=43r2) and surface area (A = r2) of each sphere? (b) How many spheres are required to give a total volume of 1.0 cm3? What is the total surface area of these spheres in square meters?