Match the following aqueous solutions with the appropriate letter from the column on the right. 1.9.00x 102 m Al(NO3)3 2.0.130 m K₂S 3.0.210 m 4.0.450 m Glucose (nonelectrolyte) CoSO4 A. Highest boiling point B. Second highest boiling point C.Third highest boiling point D. Lowest boiling point

A forensic chemist is given a white solid that is suspected of being pure cocaine (C17H21NO4, molar mass = 303.35 g/mol). She dissolves 1.22 0.01 g of the solid in 15.60 0.01 g benzene. The freezing point is lowered by 1.32 0.04C. a. What is the molar mass of the substance? Assuming that the percent uncertainty in the calculated molar mass is the same as the percent uncertainty in the temperature change, calculate the uncertainty in the molar mass. b. Could the chemist unequivocally state that the substance is cocaine? For example, is the uncertainty small enough to distinguish cocaine from codeine (C18H21NO3, molar mass = 299.36 g/mol)? c. Assuming that the absolute uncertainties in the measurements of temperature and mass remain unchanged, how could the chemist improve the precision of her results?

1. Vapor pressure: Arrange the following aqueous solutions in order of increasing vapor pressure at 25°C: 0.35 m C2H4(OH)2 (ethylene glycol, nonvolatile solute); 0.50 m sugar; 0.20 m KBr; and 0.20 m Na2SO4. C2H4(OH)2 < sugar < KBr < Na2SO4 Na2SO4 < sugar < KBr < C2H4(OH)2 sugar < C2H4(OH)2 < KBr < Na2SO4 KBr < sugar < Na2SO4 < C2H4(OH)2

Consider two hypothetical pure substances, AB(s) and XY(s). When equal molar amounts of these substances are placed in separate 500-mL samples of water, they undergo the following reactions: AB(s)A+(aq)+B(aq)XY(s)XY(aq) a Which solution would you expect to have the lower boiling point? Why? b Would you expect the vapor pressures of the two solutions to be equal? If not, which one would you expect to have the higher vapor pressure? c Describe a procedure that would make the two solutions have the same boiling point. d If you took 250 mL of the AB(aq) solution prepared above, would it have the same boiling point as the original solution? Be sure to explain your answer. e The container of XY(aq) is left out on the bench top for several days, which allows some of the water to evaporate from the solution. How would the melting point of this solution compare to the melting point of the original solution?