[ Other - Science ] Open Question : Help: Science Question!!?

I am conducting a science experiment and I am completely clueless. I am mixing separate solutions of water and oil, water and soap, and water and vinegar to see which one freezes faster and why. My hypothesis was that the water mixed with soap would freeze the fastest and i was correct. The water and soap freezed in 1 hour and 17 minutes. The water and vinegar freezed in 1 hour and 23 minutes. The water and oil has been in a freezer that has the same temperature, amount, and size cup, and it is still not frozen. It has been in there for 16 hours and 56 minutes. Why won't it freeze? And why did the other ones freeze so easy? (It is a solution of 1/3 cup of vegetable oil and 1/3 cup of water)

Source: http://answers.yahoo.com/question/index?qid=20120226055935AAgXtg9

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