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(a) Assume that you have a solution of an unknown solute inCyclohexane. If the s

ID: 678731 • Letter: #

Question

(a) Assume that you have a solution of an unknown solute inCyclohexane. If the solution has freezing point depression of9.50 C , what is the Molality of this solution. Molar freezingpoint constant is 20.2 C/m .

Molality = ?tf / M = 9.50 /20.2 = 0.470 molal.

(b) -since the thermometer used has markings for each Celsiusdegree, assume that you can be certain of the freezing pointof depression only to within ± 0.2 C .if the freezing pointof depression is measured as 9.7 C, than what molality would bereported for the solution.

Explanation / Answer

      a) depression infreezing point    Tf = Kf x molality                                                        9.5oC= (20.0 C /m ) x molality                                                      molality = 9.5 / 20.2                                                                   = 0.470 m       b) If the freezing pointdepression is 9.7oC                                                    molality = 9.7 / 20.2                                                                       = 0.480m