It is a phenomenon that has baffled the world’s brightest minds since the time of Aristotle.
Now a team of physicists believe they may have solved the centuries old mystery of why hot water freezes faster than cold water.
Known as the Mpemba effect, water behaves unlike most other liquids by freezing into a solid more rapidly from a heated state than from room temperature.
russ_watters said:Just to be clear: while the wording of the news article makes it sound like this always occurs, in fact it almost always does not. Special/unusual experimental setups may sometimes enable it to occur.
See the similar discussions links for past discussions including a semi-scientific test I ran once to see if the phenomena would occur (it did not).
Yes. In one of the links below (if you can't find it I'll look later), is details of a test where I put 3 or 4 coffee cups with equal amounts of water at various temperatures into a freezer, with a temperature logger probe in each. The profiles were nearly exactly as expected.PeroK said:There is too much ice cream in the freezer compartment for me to try it straight away, but I was going to put a cup of boiling water and a cup of water at room temperature in there to see which one froze first. I guess, from what you're saying, the cup at room temperature would freeze first, as one would expect?
We'll help.HallsofIvy said:Well, if there is too much ice cream in the freezer, you will just have to sacrifice yourself, like a true scientist, and eat all that ice cream to empty the freezer!
There are several theories as to why hot water freezes faster than cold water. One theory is the Mpemba effect, which suggests that the molecules in hot water are more likely to align in a way that promotes rapid freezing. Another theory is that hot water has a lower dissolved gas content, making it easier for the water molecules to form ice crystals. However, the exact reason is still not fully understood and is still a topic of ongoing research.
No, it is not always true that hot water will freeze faster than cold water. The Mpemba effect and other factors that may contribute to hot water freezing faster are dependent on various conditions such as the starting temperature of the water, the container it is in, and the surrounding environment. In some cases, cold water may freeze faster than hot water.
Yes, the type of water can affect the freezing rate. For example, distilled water may freeze faster than tap water because it has a lower dissolved gas content. Additionally, the presence of impurities, such as minerals or particles, can also affect the freezing rate of water.
Yes, the size of the container can affect the freezing rate of hot water. A larger container will have a larger surface area, allowing for more heat to escape and the water to cool faster. This can lead to the hot water freezing faster than it would in a smaller container.
Understanding the factors that can affect the freezing rate of water can be useful in various applications, such as in industrial processes, food preservation, and weather forecasting. It can also provide insights into the behavior of water molecules and help in furthering our understanding of thermodynamics and phase transitions.