Upon trying to determine the freezing point depression constant of cyclohexane in last week's general chem lab, I obtained a value of 55.4 rather than the theoretical value of 20.2degC/molal . This was done by recording and graphing the temperature of a naphthalene/cyclohexane solution in an ice bath.
The teacher said my graphs were ok, and my lab partner came up with the same Kf in her calculations. Did we do the lab wrong?
In doing my lab report I'd like to go beyond saying "this was a non ideal solution". Assuming I got good results, what is it with the interaction of napthalene/cyclohexane which causes this behavior?
As naphthalene shouldn't to my knowledge dissociate in cyclohexane the vant hoff factor is irrelevant here IMHO. However I did see naphthalene is flat and know cyclohexane has conformations through which it constantly switches; I don't see how this could cause such a negative devation from Raoult's vapor pressure law... Through my eyes it seemed that the cyclohexane and naphthalene should have a positive deviation. Although they both normally interact through london dispersion forces it seems they'd get in each others way by their different shapes.
I saw this article, "solubilities of biphenyl and naphthlane in benzene and cyclohexane" whose abstract states they obtained results like ours, but I can't read Korean so the rest is useless to me.
http://www.cheric.org/PDF/HHKH/HK25/HK25-4-0372.pdf