Help with Mpemba Effect Experiment

[Edgeworth]

I need help to fill in the holes about my project. This is the project's website https://www.sciencebuddies.org/mentorin ... p032.shtml . How should I warm up my beaker? The metal plate I was using became red from warming it up on the stove. I also want to know if I should cover the beaker with plastic wrap and put the thermometer inside the wrap because I always have to keep taking off the cover then putting it back on after I take the temperature when I'm warming it up on the stove. Also, would a meat thermometer do well to measure the temperature of the water? The place I bought my beakers from were out of partial immersion thermometers.

[deleted-71709]

This sounds like a really interesting experiment. I remember discussion this phenomenon in physics class when I was in college.

I wouldn't worry too much about the metal plate getting red on the stove. That means it's getting up to about 1000 degrees F. That means you have the stove turned up too high. Just turn it down. You don't need that much heat to warm your water. It will take a bit longer to raise the temperature of your water, but lowering the heat will make it safer.

I think using plastic wrap to cover your beaker during heating is a good idea. But it you get the water up to boiling, it may become very soft and either come off the beaker or fall in. Experiment carefully at temperatures that aren't so high to start with.

Using a meat thermometer will be fine. You just need to make sure you immerse it the same amount in the water every time you take a measurement. Most meat thermometers are sensitive to how far you insert them into the meat. Usually about half way works best.

I have one suggestion about the "experimental procedure". I would weigh the beaker and water before I heated it. It would just be easier than working with a hot beaker and trying to do it quickly.

Good luck and have fun.

[Edgeworth]

I get what you're saying, but should I take off the plastic wrap if I wanted it to evaporate in my freezer? Also, what categories should I include in my data table? (Like temperature of water, or time taking to reach 0 degrees)

[deleted-71588]

but should I take off the plastic wrap if I wanted it to evaporate in my freezer?

That would depend on the exact wording of your hypothesis.
If you have a sealed environment (air/gas over liquid/solid), the behavior will differ than if you have an open container. If you use a sealed container, then you need to make sure that ALL of your samples have the same volume/pressure/temperature of gas to start with. That would make the experimental proceedure more complicated, so I hope that your hypothesis can be tested using open containers.

I would weigh the beaker and water before I heated it.

During the heating process, evaporation can occur and that might introduce some error in terms of different masses of samples going into the freezer. I would conduct a side measurement experiment to determine if the mass differences between weighing samples at room temperature prior to heating and the heated samples (using the highest temperature you intend to use, with the longest time to heat them, with the smallest sample size you intend to use)intend to use to heat them) are statistically significant. In this case statistical significance would be whether the difference is less than your ability to reliably measure the difference in the number of samples you intend to use.

[Edgeworth]

Wouldn't the plastic wrap hold in all the water and prevent evaporation during the heating process?

[deleted-71588]

Wouldn't the plastic wrap hold in all the water and prevent evaporation during the heating process?

If the plastic wrap makes a gas tight seal, then the gas inside will try to expand as the temperature is raised so the pressure will increase or the plastic wrap will act like a ballon. If the plastic wrap does not make a gas tight seal, then gas will escape. Look up "ideal gas law" for an explaination of this.

In either case, when you remove the plastic wrap, the pressure will equalize (if it didn't happen earlier) and you will loose some water mass as water vapor somewhere in the process. There is also the possibility that water vapor condenses on the plastic wrap and when you remove it, there goes some water mass.

What I can't know is how much water mass is involved in your experimental conditions which is why I recommended that you attempt to measure it in a couple of trials and see if it is measurable. If it isn't measurable, then it obviously isn't enough matter to matter.

[Edgeworth]

Also, I'm getting a result that completely contradicting the effect. The cold water gets to 0 degrees faster than the hot water. What should I do?

[deleted-71588]

Also, I'm getting a result that completely contradicting the effect. The cold water gets to 0 degrees faster than the hot water. What should I do?

Welcome to the world of experimental physics for less than well understood phenomonen. Because the Mpemba effect is not yet understood, I'm at a loss to offer any suggestions on things to try.

Your experiments show that the phenomonen does not exist for the conditions you tested. That is a viable result that matches observations by lots of people; however, Aristotle, Francis Bacon, Rene Descartes, and others have observed the Mpemba effect under some circumstances that haven't been fully characterized and understood. How your conditions differ from ones where the effect is observed is anybody's guess. One would have to do a lot of carefully controlled experiments and be lucky enough to reproducably observe the phenomonen and document the differences in conditions that it exists and doesn't exist in order to help understand the effect. That has yet to be done.

My suggestion is to write up your experiment and document your test conditions as best that you can and draw the conclusion that Mpemba effect did not exist in your experimental conditions.

[Edgeworth]

Thank you both for helping me with this experiment. My science teacher basically told me the same thing as you did. All I need to do is just a few more trials and I'll have all my data collected. Thanks again for all the help.