Workshop CHE 168
Problem Set #3
1. Calculate the molality of each of the following solutions:
(a) 13.0 g of benzene, C6H6, dissolved in 17.0 g carbon tetrachloride, CCl4
(b) 2.1 g of sulfur, S8, dissolved in 95.0 g of naphthalene, C10H8
(c) 1.50 mol of NaCl dissolved in 15.0 mol water.
2. A sulfuric acid solution containing 571.6 g of H2SO4 per liter of solution has a density of 1.329 g/cm3. Calculate(a) the per cent by mass
(b) the mole fraction
(c) the molality
(d) the molarity of H2SO4 in this solution.
3. Commerical concentrated aqueous ammonia is 28% NH3 by mass and has a density of 1.42 g/mL. What is the molarity of this solution?4. Calculate the number of moles of solute present in each of the following solutions:
(a) 214 mL of 0.122 M MgCl2
(b) 60.0 g of an aqueous solution that is 1.25% KI by mass
(c) 250 g of an aqueous solution that is 0.460% NaCl by mass
(d) 0.600 L of 1.25 M H2SO4.
5. Calculate the freezing and boiling points of each of the following solutions:(a) 0.45 m ethylene glycol in ethanol
(b) 5.0 g CsI in 50.0 g of water
(c) 0.15 m glucose in ethanol
(d) 27.5 g of sucrose, C12H22O11, in 80.0 g of water.
6. An aqueous solution freezes at - 8.95 oC. What is the boiling point of the solution?7. Lauryl alcohol is obtained from coconut oil and is used to make detergents. A solution of 5.00 g of lauryl alcohol in 0.100 kg of benzene freezes at 4.1 oC. What is the molar mass of this substance?
8. Lysozyme is an enzyme that breaks bacterial cell walls. A solution containing 0.150 g of this enzyme in 210 mL of solution has an osmotic pressure of 0.953 torr at 25 oC. What is the molar mass of this substance?