Homework Chapter 13 CHEM 1212K Spring 2014 1. The solubility of Ar in water at 25°C is 1.6 × 10-3 M when the pressure of the Ar above the solution is 1.0 atm. Calculaete the solubility of Ar at a pressure of 2.5 atm. 2. (a) Calculate the mass percentage of NaCl in a solution containing 2.50 g of NaCl in 50.0 g of water. (b) A commercial bleaching solution contains 3.85 mass % sodium hypochlorite, NaOCl. What is the mass of NaOCl in a bottle containing 2.50 kg of bleaching solution? 3. A solution is prepared by dissolving 23.7 g of CaCl2 in 375 g of water. The density of the resulting solution is 1.05 g/mL. Calculate the molal concentration of CaCl2 in this solution. 4. Calculate (a) the mole fraction (b) malality of urea (MW = 60.0 g/mol) in a solution prepared by dissolving 16 g of urea in 39g of H2O. 5. A sulfuric acid solution containing 571.6 g H2SO4 per liter of solution has a density of 1.392 g/mL. Calculate (a) the molality, (b) the mole fraction, and (c) the molarity of sulfuric acid in the solution. 6. The vapor pressure of pure ethanol at 60°C is 0.459 atm. Calculate the vapor pressure, using Raoult's Law, of a solution prepared by dissolving 10.0 mmol naphthalene (nonvolatile) in 90.0 mmol ethanol. 7. What is the freezing point (°C) of a solution prepared by dissolving 11.3 g of Ca(NO3)2 (formula weight = 164 g/mol) in 115 g of water? The molal freezing point depression constant for water is 1.86°C/m. 8. A solution is prepared by dissolving 0.60 g of nicotine (a nonelectrolyte) in water to make 12 mL of solution. The osmotic pressure of the solution is 7.55 atm at 25 °C. Calculate the molecular weight of nicotine. 9. Camphor (C10H16O) melts at 179.8 °C, and it has a particularly large freezing-pointdepression constant, Kf = 40.0 oC/m. When 0.186 g of an organic substance of unknown molar mass is dissolved in 22.01 g of liquid camphor, the freezing point of the mixture is found to be 176.7 oC. What is the molar mass of the solute? 10. A sample of 2.05 g of polystyrene of uniform polymer chain length was dissolved in enough toluene to form 0.100 L of solution. The osmotic pressure of this solution was found to be 1.21 kPa at 25 0C. Calculate the molar mass of the polystyrene.