#1
Hey, so as part of a project in science class, my partner and I had to distill this jar of whatever.

Anyway, one of the substances is rubbing alcohol. We know this because we've run other tests on it. The thing is, the boiling point of rubbing alcohol is 82.23 degrees celcius. Our rubbing alcohol did start boiling at that temperature, but then it plateaued at 84 degrees for a couple minutes as it was boiling.


Can anyone tell me why it plateaued at 84 instead of 82?
#2
Different substances can change the boiling temperature/freezing point of substances (like salt in water). That's a possibility. Probably the most likely.
#3
Yeah, impurities alter the equilibrium point of the phase transition.
#5
Quote by hawk5211
could also depend on the pressure, if you are at higher altitude, as in PV=nRT



Of course, who couldn't see this.

/sarcastic remark
#6
The boiling point isn't a constant value...

It depends on the purity of the substance as well as the atmospheric conditions around it.
Looking for my India/Django.
#7
Quote by excalibur672
Different substances can change the boiling temperature/freezing point of substances (like salt in water). That's a possibility. Probably the most likely.

Thanks. The teacher'll like that explanation.


In fact, one of the other substances we found in our smush was salt that had been dissolved.

#8
Same thing happened to me when I did a distillation lab. There's probably still some impurities or traces of the other substances you distilled still in the alcohol.
#9
Those basic values are done at 'standard conditions' so 1atm and 25degrees; plus it might be impure, so it can vary around that mean value you were given