Aveneu Park, Starling, Australia

The refrigerated and one warmer milk carton. When

The Mpemba EffectPhysicsDoes Hot Water Freeze Quicker than Cold Water ?__________________________________________Signature of Sponsoring Teacher___________________________________________Signature of school Science Fair Coordinator TeacherRaymond Sansonetti3009 W. Cornelia.Chicago, IL 60618Grade 7Table of ContentsAcknowledgements                                                                       Page 3Purpose and Hypothesis                                                                Page 4 Review of Literature                                                                     Page 5-6Materials and Procedure                                                               Page 7Results and Conclusion                                                                Page 8-9Reflection and Application                                                          Page 10Reference List                                                                              Page 11-12Acknowledgements I would like to thank both of my parents. My mom and dad both helped with testing by running the experiment when I was not around. They also provided the materials necessary to complete testing. I would also like to thank Ms. Machado for providing all outlines and necessary information to help me complete my project. Also a big part of my project was research and Chicago Public libraries always help me discover and learn new information so I would like to thank the, as well.  Purpose and Hypothesis Throughout this project I have been trying to discover the question, does hot water freeze faster than cold water? I hypothesized yes, hot water does freeze faster than cold water, mainly having to do with the fact that cold water will be less dense, so less matter to freeze.  However as I begin testing temperatures that are colder, such as 50 degrees Celsius and 30 degrees Celsius,  I expect to start seeing cold water freezing first, because once water reaches a certain point, it will stop becoming more dense, and begin becoming less dense until it becomes ice, this putting the cold water in a position where it is so close to frozen already, it doesn’t matter which cup is freezing quicker.Review of Literature The Mpemba effect is the effect that hot water freezes faster than cold water (Helmenstine, 2016). This fact was first discovered by Aristotle, but people soon started questioning it, as it does not seem like it would make much sense, eventually almost no one believed in the Mpemba effect (Jeng). That is, until 1968 when it was rediscovered by Erasto Mpemba when making ice cream in his baking class (Dean). He forgot to refrigerate one of his milk cartons before freezing the milk, and he froze some milk cartons that were refrigerated and one warmer milk carton. When checking up on the milk, he noticed that the warm milk had frozen before any of the other cartons. He told his mentor, who eventually passed it onto a prestigious scientist who further researched this, showing it to the world, in turn rediscovering the Mpemba Effect. After this, many more scientists discovered this and it is now known that water freezes quicker when warm. Even though scientists have tested and retested this, they still do not know why the Mpemba effect works (Dean). They think it could be a variety of things, such as when cold the very surface of water develops a slight icey cover that insulates the water and protects it from extreme temperatures (Edwards). Another way could be when cold, water would be more dense, so there is more matter to freeze (Griffiths, 2013). However, water will not always be more dense when colder (Blog, 2013). As water gets to a certain density, it reaches maximum density, and from there continues to grow less dense until it reaches ice, hence why bodies of water freeze from the surface down, making life on Earth near impossible. This maximum density is reached at 4 degrees celsius, before it begins its decrease in density (Kurtus). A different possible way that hot water freezes faster is it has more energy, therefore become more easily manipulated (Heffner, 2001). However, as the temperatures become closer, results may vary regardless of any science having to do with the project (Jeng). It would be too random.Materials and Procedure The materials I used include the following, four plastic (see through) cups, a thermometer, water (different temperatures used). Each of the cups was filled with water and had water with different temperatures. Using a thermometer, I made sure that one cup had 60° celsius water in it, another had 50° celsius water, another had 20° water, then finally the last one had 10° water. I placed them all in the freezer. Every half hour hour I check them, using the thermometer, again, to measure the water. I chart the temperatures at every check in and end the experiment when every cup has frozen. One cup has 60° celsius water in it, another had 50° celsius water, another had 20° water, then finally the last one had 10° waterCreate a table for the data.Place the cups inside the freezerEvery 30  minutes check on the cups of water to find out the temperatures.Repeat process 2 more times then take averages.Results            Check-In # (Every ½ hour)12345678910temp.10°7°3°0.7°0.5°-0.1°-0.3-0.4FZN*FZN*FZN*in20°13°7°3°0.6°0.1°-0.3-0.3-0.4FZN*FZN*Degrees50°19°13°8°5°1°0.2°-0.3-0.4FZN*FZN*Celsius60°24°16°7°3°0.4°-0.1-0.3-0.4FZN*FZN**FZN abbreviates frozenBegins freezing process: Ice coating surfaceWater around edge of cup has frozenAll water cups are nearly indistinguishable at this point. Ice has become more than an inch deep on the surfaceConclusion In conclusion, my data proved to stray from my hypothesis in some ways, but stuck to my initial hypothesis in other ways. I hypothesized that hot water freezes faster than cold water does. My data shows that on average, the colder temperatures will freeze first, contradicting my research and hypothesis. Very clearly, multiple times, cold water froze before the hot water. This would be evidence to prove the Mpemba Effect a myth. However, while cold water froze first, hot water had a much more rapid decrease in temperature and it came extremely close to freezing before the cold water on all three of the tests. This would be evidence proving the Mpemba Effect is real.If I had used different, warmer, temperatures the hot water might have frozen before the cold water. Other than that, I think my project is completely controlled with very minor flaws in any. ReflectionEven though the results did not come out as expected, it could be because the temperatures were too close together. When researching the topic, I did find out that in past experiments on this same topic, many scientists have found that the cold water will freeze quicker if the temperatures are too close to each other. Since this is the case, instead of having the temperatures 30° celsius apart from each other, it would be better if they were 40° or even 50° celsius apart from each other. Besides the water temperatures being too close together, I think the experiment was fair and controlled, and even if the data did not follow my prediction, it still gave me important information about what need to be done so that it does correspond with my hypothesis.ApplicationThis experiment couldn’t probably directly influence the world itself, but it does provide scientists, more specifically physicists, with an important principle to work with. The colder a liquid is, the slower it will freeze compared to a warmer liquid. People could use this when working with all molecules in general. Since molecules from a warmer substance are more mobile and active, they will be more easily manipulated. The reason why water freezes faster when warm is still not confirmed, but one reason could be that ice is, in fact, less dense than water. This explains why lakes freeze from the top down, rather than the bottom up. It also explains why icebergs, as heavy and big as they are, still float no matter the shape or size.Reference ListBlog, T. P. (2013, October 29). Why Hot Water Freezes Faster Than Cold-Physicists Solve the Mpemba Effect. Retrieved November 19, 2017, from https://medium.com/the-physics-arxiv-blog/why-hot-water-freezes-faster-than-cold-physicists-solve-the-mpemba-effect-d8a2f611e853Dean, S. (n.d.). Why Does Hot Water Freeze Faster Than Cold Water? Retrieved November 19, 2017, from http://www.sciencealert.com/why-does-hot-water-freeze-faster-than-cold-waterEdwards, L. (n.d.). Mpemba effect: Why hot water can freeze faster than cold. Retrieved November 19, 2017, from https://phys.org/news/2010-03-mpemba-effect-hot-faster-cold.htmlGriffiths, S. (2013, November 01). Mystery of why hot water freezes faster than cold is solved – and it’s all down to the strange behaviour of atom bonds. Retrieved November 19, 2017, from http://www.dailymail.co.uk/sciencetech/article-2483383/Mystery-hot-water-freezes-faster-cold-solved–strange-behaviour-atom-bonds.htmHeffner, H. (2001, January). The Mpemba Effect PDF.Helmenstine, P. A. (2016, May 09). Mpemba Effect: When Hot Water Freezes Faster Than Cold. Retrieved November 19, 2017, from https://www.thoughtco.com/the-mpemba-effect-definition-609415Jeng, M. (n.d.). Can hot water freeze faster than cold water? Retrieved November 19, 2017, from http://math.ucr.edu/home/baez/physics/General/hot_water.htmlJeng, M. (n.d.). Hot water can freeze faster than cold?!? PDF. New York: Physics Department.Kurtus, R. (n.d.). Mpemba Effect: When Hot Water Freezes before Cold. Retrieved November 19, 2017, from http://www.school-for-champions.com/science/mpemba.htm#.WfZhU7pFyUkSalinas, K. (2015, January 18). Unsolved Mysteries: The Mpemba Effect. Retrieved November 19, 2017, from http://www.yalescientific.org/2015/01/unsolved-mysteries-the-mpemba-effect/