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13 Properties of Solutions Solutions to Exercises = Kb m; m = Kb = +0.49 = = 0.098 m adrenaline mol adrenaline adrenaline m = = kg adrenaline kg MM adrenaline = m g adrenaline kg = 0.0976 0.64 m g adrenaline 0.0360 kg = 1.8 10² g/mol adrenaline Check. The molecular formula is MM = 183 g/mol. The values agree to 2 sig figs, the precision of the experimental value. 13.80 = 5.5 4.1 = 1.4; m = = 5.12 1.4 = = m MM lauryl alcohol = g m lauryl X alcohol = 0.273 5.00 g X lauryl 0.100 kg alcohol C₆H₆ = 1.8 10² g/mol lauryl alcohol 13.81 Anayze/Plan. Follow the logic in Sample Exercise 13.12. Solve. = MRT; M = 0.953 torr X 760 atm torr X 0.08206 mol K atm 298 1 K = 5.128 10⁻⁵ = 5.13 10⁻⁵ M mol = M L = 5.128 10⁻⁵ X 0.210 L = 1.077 10⁻⁵ = 1.08 10⁻⁵ mol lysozyme MM = mol g = 1.077 0.150 10⁻⁵ = 1.39 10⁴ g/mol lysozyme 13.82 M = P/RT = 0.605 298 0.08206 mol- K atm = 0.02474 = 0.0247 M MM = g = 0.02474 = 380 g/mol 13.83 (a) Analyze/Plan. i = П (measured) / П (calculated for a nonelectrolyte); П (calculated) = M RT. Solve. П (calculated) = 0.010 L 0.08206 mol K - atm 298 K = 0.2445 = 0.24 atm i = 0.674 atm/0.2445 atm = 2.756 = 2.8 (b) The van't Hoff factor is the effective number of particles per mole of solute. The closer the measured i value is to a theoretical integer value, the more ideal the solution. Ion-pairing and other interparticle attractive forces reduce the effective number of particles in solution and reduce the measured value of i. The more concentrated the solution, the greater the ion-pairing and the smaller the measured value of i. 13.84 If these were ideal solutions, they would have equal ion concentrations and equal values. Data in Table 13.4 indicates that the van't Hoff factors (i) for both salts are less than the ideal values. For 0.030 m NaCl, i is between 1.87 and 1.94, about 1.92. For 384