lab question

[gretel789]

In an experiment called " molar mass determination by freezing point depression" we determined the freezing point of cyclohexane, by placing a test tube of this substance in a slurry bath until it freezes (reached O degrees c), thawing it and repeating the process. My question is, if some of the cylohexane evaporates during the experiment how would it affect the change in temperature? my guess is that the temperature would decrease quicker?

thanks

[valdorod]

When calculating the freezing point of just the solvent (cyclohexane), any loss of volume or mass will not affect the freezing point.  Freezing point of pure substances is an intensive property, as such it is independent of the amount.

For a solution, however, any loss of solvent concentrates the solution making ΔTf larger.