The freezing point of pure benzene (C,H,) is 5.50°C. The freezing point of a solution containing 5.00 g of an unknown non-dissociating solute in 444 g of benzene is 5.07°C. K, of benzene = 4.90°C/m. Show complete calculations for each question below.

Water at 25 C has a density of 0.997 g/cm3. Calculate the molality and molarity of pure water at this temperature.

Sodium chloride (NaCl) is commonly used to melt ice on roads during the winter. Calcium chloride (CaCl2) is sometimes used for this purpose too. Let us compare the effectiveness of equal masses of these two compounds in lowering the freezing point of water, by calculating the freezing point depression of solutions containing 200. g of each salt in 1.00 kg of water. (An advantage of CaCl2 is that it acts more quickly because it is hygroscopic, that is. it absorbs moisture from the air to give a solution and begin the process. A disadvantage is that this compound is more costly.)

A patient has a “cholesterol count” of 214. Like manyblood-chemistry measurements,this result is measured inunits of milligrams per deciliter (mgdL1). Determine the molar concentration of cholesterol inthis patient’s blood, taking the molar mass of cholesterolto be 386.64gmol1. Estimate the molality of cholesterol in the patient’sblood. If 214 is a typical cholesterol reading among men inthe United States, determine the volume of such bloodrequired to furnish 8.10 g of cholesterol.

An unknown compound contains only carbon, hydrogen, and oxygen. Combustion analysis of the compound gives mass percents of 31.57% C and 5.30% H. The molar mass is determined by measuring the freezing-point depression of an aqueous solution. A freezing point of 5.20C is recorded for a solution made by dissolving 10.56 g of the compound in 25.0 g water. Determine the empirical formula, molar mass, and molecular formula of the compound. Assume that the compound is a nonelectrolyte.

Beaker A has 1.00 mol of chloroform, CHCl3, at 27C. Beaker B has 1.00 mol of carbon tetrachloride, CCl4, also at 27C. Equal masses of a nonvolatile, nonreactive solute are added to both beakers. In answering the questions below, the following data may be helpful. Write , =, or more information needed in the blanks provided. (a) Vapor pressure of solvent over beaker B vapor pressure of solvent over beaker A. (b) Boiling point of solution in beaker A boiling point of solution in beaker B. (c) Vapor pressure of pure CHCl3 vapor pressure of solvent over beaker A. (d) Vapor pressure lowering of solvent in beaker A vapor pressure lowering of solvent in beaker B. (e) Mole fraction of solute in beaker A mole fraction of solute in beaker B.

Vapor-pressure lowering is a colligative property, as are freezing-point depression and boiling-point elevation. What is a colligative property? Why is the freezing point depressed for a solution as compared to the pure solvent? Why is the boiling point elevated for a solution as compared to the pure solvent? Explain how to calculate T for a freezing-point depression problem or a boiling-point elevation problem. Of the solvents listed in Table 10-5, which would have the largest freezing-point depression for a 0.50 molal solution? Which would have the smallest boiling-point elevation for a 0.50 molal solution? A common application of freezing-point depression and boiling-point elevation experiments is to provide a means to calculate the molar mass of a nonvolatile solute. What data are needed to calculate the molar mass of a nonvolatile solute? Explain how you would manipulate these data to calculate the molar mass of the nonvolatile solute.