Re: Why does Corn Oil freeze at a lower temp than water

Tough question to answer...  Let's step back and think a bit about what is 
happening when these liquids are freezing.  The water molecules (easiest 
example) align themselves during the freezing process into well-organized 
regular lattices.  These molecules are looking for an optimal low-energy 
state, easiest to maintain in a simple structure.

Adding impurities to the water, like your sugar water sample, will 
change the nature of the lattice.  The water wants to freeze in a pure form 
 (it is easier) so the sugar solution actually concentrates in the unfrozen 
liquid portion as ice crystals are forming.  The more concentrated the 
sugar solution becomes, the more difficult it becomes to freeze the 
still unfrozen portion.  It isn't really the sugar that is freezing, it is 
the water, trapping the sugar molecules in its lattice.

So, moving back to the corn oil - there are a lot of molecular forces going 
on between these high molecular weight molecules.  I don't have details 
with me (I am sure you can find information about corn oil composition at 
your library), but corn oil is made up of a large variety of different 
long-chained organic compounds.  Freezing these long chains is going to 
require a lot of energy because you are trying to 'organize' them into 
a rigid lattice structure.  Think of it like the difference between making 
a tower out of Lego or making it out of cooked spaghetti.  One requires a 
lot more work on your part.

So, I don't think I have answered your question with the quantitative 
thermodynamics you were probably expecting, but you have more information 
about the difference in energy requirements than I do at the moment.  So, 
congratulations on a good experiment and I hope you are having fun!

Kieran