5. The molar mass of an unknown solid, which is nonvolatile and a nonelectrolyte, is to be determined by the freezing-point depression method. The pure solvent used in the experiment freezes at 10C and has a known molal freezing-point depression constant. Kf. Assume that the following materials are also available. -testtubes-beaker-stirrer-stopwatch-pipet-graphpaper-thermometer-hot-waterbath-balance-ice (a) Using the two sets of axes provided below, sketch cooling curves for (i) the pure solvent and for (ii) the solution as each is cooled from 20C to 0.0C. Pure Solvent Solution (b) Information from these graphs may be used to determine the molar mass of the unknown solid. (i) Describe the measurements that must be made to determine the molar mass of the unknown solid by this method. (ii) Show the setup(s) for the calculation(s) that must be performed to determine the molar mass of the unknown solid from the experimental data. (iii) Explain how the difference(s) between the two graphs in part (a) can be used to obtain information needed to calculate the molar mass of the unknown solid. (c) Suppose that during the experiment a significant but unknown amount of solvent evaporates from the test tube. What effect would this have on the calculated value of the molar mass of the solid (i.e., too large, too small, or no effect)? Justify your answer. (d) Show the setup for the calculation of the percentage error in a student's result if the student obtains a value of 126gmol1 for the molar mass of the solid when the actual value is 120.gmol1