Science Buddies: "Ask an Expert"

Hi i'm doing my project on the mpemba effect and I was wondering if should time the time it takes for the water to reach 0 degrees celsius first or if I should time it take for it to actually freeze. I'm asking this because the cooler water might reach 0 degrees celsius first but supercool and not freeze first so therefore I'm afraid my data may not support my hypothesis.

Hello Adrian4life2,

This is a very interesting topic. I remember having discussions about it when I was in engineering school, many years ago.

As you did not state your hypothesis, I'm not certain my advice that follows will answer your question or not.

As the ScienceBuddies project description states, there are many variables in this experiment - some of them understood and some of them perhaps not understood well - that must be controlled VERY CAREFULLY for the experiment to be successful.

The project description specifically states to measure the time at which the water reaches 0C. I think this is important. It is difficult to determine at what time freezing actually occurs. Typically very small crystals of ice begin to form in what seem to be random locations in the liquid. This is the actual beginning of freezing, and is very hard to detect. So measuring when 0C is measured is very much more simple to do, and more accurate.

The accuracy of the time to reach 0C is highly dependent on exactly where in the beaker of liquid the temperature is made. Be certain your temperature measuring device is placed in EXACTLY the same spot inside the beaker for all measurements.

Also be careful to control the conditions of the freezer you use. All the types of heat transfer - conduction, convection, evaporation and radiation - likely contribute to how fast the water freezes. The conditions inside the freezer play a large role in this.

I hope this helps.

Have fun with this experiment!