Hot water freezes faster than cold?

In summary, the Mpemba effect is a phenomenon where hot water can freeze faster than cold water, which has been observed since ancient times. The exact reason for this is still debated, but it is believed that hot water loses more heat through evaporation and may have a lower dissolved gas content. However, it is not recommended to use hot water to make ice cubes as it can lead to uneven freezing and potential damage. The Mpemba effect has been observed in other liquids as well, but more research is needed to fully understand it. While it may have practical applications, other factors such as the container shape and size, water purity, and presence of impurities can also affect the freezing rate of water.
  • #1
Einstein Mcfly
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http://www.iflscience.com/chemistry/hot-water-freezes-faster-cold-and-now-we-know-why

I thought that this had never been shown to happen with closed containers. I always thought that this was an issue of open containers allowing for evaporation and hence a smaller amount of frozen water, and that if lids were put on then the cold froze faster.

Does anyone have any thoughts on the vague explanation proposed in this link?
 
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1. Why does hot water freeze faster than cold water?

This phenomenon is known as the Mpemba effect and has been observed since ancient times. The exact reason is still debated, but it is believed that hot water loses more heat through evaporation which speeds up the cooling process. Additionally, hot water may have a lower dissolved gas content, making it easier to freeze.

2. Does this mean I should use hot water to make ice cubes faster?

No, it is not recommended to use hot water to make ice cubes as it can lead to uneven freezing and potentially damage your ice tray. It is also important to note that the Mpemba effect is not always observed and can depend on various factors such as the temperature of the hot and cold water, the container used, and the surrounding environment.

3. Is this phenomenon only observed with water or can other liquids freeze faster when hot?

The Mpemba effect has been observed in other liquids such as milk, beer, and alcohol, but it is not as well studied as in water. It is believed that the same principles apply, but further research is needed to fully understand the effect in other liquids.

4. Can the Mpemba effect be used in practical applications?

While the Mpemba effect may seem counterintuitive, it has been studied for potential practical applications. For example, it has been suggested that using hot water to de-ice airplane wings may be more efficient and that hot water pipes may freeze faster than cold water pipes in extreme cold weather.

5. Are there any other factors that can affect the freezing rate of water?

Yes, the freezing rate of water can also be affected by factors such as the shape and size of the container, the purity of the water, and the presence of impurities or additives. These factors can all influence the rate at which heat is transferred and the formation of ice crystals, ultimately affecting the freezing time.

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