Uncategorized

Hot water freezes faster than cold water

Water is one of the most mysterious compounds available on earth. For example most liquids achieve maximum density as they cools but water reaches a state of maximum density at 4°C and then becomes less dense.
Then there is the strange Mpemba effect, named after a Tanzanian student who discovered that a hot ice cream mix freezes faster than a cold mix in cookery classes in the early 1960s. (In fact, the effect has been noted by many scientists throughout history including Aristotle, Francis Bacon and René Descartes.)
The effect has been measured on many occasions with many explanations put forward. One idea is that warm containers make better thermal contact with a refrigerator and so conduct heat more efficiently.Hence the faster freezing. Another is that warm water evaporates rapidly and since this is an endothermic process, it cools the water making it freeze more quickly.
None of the explanations are convincing or proven but talking about best explanation
till date, Xi Zhang at the Nanyang Technological University in Singapore and a few pals provide one. These guys say that the Mpemba paradox is the result of the unique properties of the different bonds that hold water together.
References:
1.) https://medium.com/the-physics-arxiv-blog/why-hot-water-freezes-faster-than-cold-physicists-solve-the-mpemba-effect-d8a2f611e853
2.) http://www.iflscience.com/chemistry/hot-water-freezes-faster-cold-and-now-we-know/
3.) https://sciencealert.com/does-hot-water-really-freeze-faster-than-cold-water

Author

pallav

Leave a comment

Your email address will not be published. Required fields are marked *