Using the previously calculated Kf, the molar masses of unknown substances A, C, and D were able to be calculated. However, given that the original Kf was slightly larger than the theoretical value, the molar masses were significantly higher than the masses using the theoretical value as shown...
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...s measured as well as the mass of 10 drops of toluene, the solute. The temperature of the solution rose to the freezing point after supercooling, then continued to drop as the solution froze, versus stabilizing as the pure p-xylene did. The maximum temperature obtained after supercooling was recorded as the freezing point of the solution. This process was repeated three times, each with a new test tube and the same beaker and scale for measuring the masses, then the Tf was calculated for each trial, as well as the average Kf. For the final portion of the lab, the same procedure as above was followed with the substation of 10 drops of unknown solutes instead of toluene in the p-xylene. Each unknown, A, C, and D, had one trial each. With the experimentally gathered data, the molar masses were then computed and compared to the given compound molar masses to identify.
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