[muddymoose]

I performed a microscale fractional distillation on a mixture of two organic liquids.  The two liquids were from a list of five potential liquids (hexane, cyclohexane, heptane, toluene, and ethylbenzene).  The task was to identify the two liquids present.

The temperature of the vapor first stabilized at about 80C, indicating it was cyclohexane.  No problem there.

The temperature then started dipping and fluctuating a few degrees.  It then dropped about ten degrees, so I sank the flask deeper in the sand bath and pushed sand up around it.  The temperature then increased at a somewhat irregular rate before peaking briefly at 130C.  It then dropped off and the liquid was practically gone from the distillation flask.

Here's the confusing part to me...toluene's BP is around 111C, and ethylbenzene is around 136C.  So if it peaked around 130C, which could it have been? 

On one hand, it seems that if I heated it too aggressively, it could have been toluene heated past its BP?  This seems like a stretch since it was well past the toluene BP.

On the other hand I think it could have been ethylbenzene.  It seems that although I didn't hit the BP, the near-BP temperature could have evaporated most of it?

Any insight would be greatly appreciated.