What’s Your Eddy IQ – Does Hot Water Freeze Faster than Cold Water?

Nadine Evans

This week we asked our Facebook followers a simple question: True or False? Hot water freezes faster than cold water.

The answer was more than a little surprising. Conventional wisdom has had many of us filling water trays with hot water to help the ice freeze faster. This may seem illogical, as hot water first has to cool and then freeze, so how is it possible for hot water to freeze faster than cold water? Yet, most ice cube tray fillers will tell you: use hot water!

To get to the bottom of this question, we searched the Internet far and wide, and settled on Scientific American as a source. Their answer? “Not usually, but possibly under certain circumstances.” Specifically, they state:

“It all depends on how fast the cooling occurs, and it turns out that hot water will not freeze before cold water but will freeze before lukewarm water. Water at 100 degrees C, for example, will freeze before water warmer than 60 degrees C but not before water cooler than 60 degrees C.” (Source). They elaborate further, stating “Another situation in which hot water may freeze faster is when a pan of cold water and a pan of hot water of equal mass are placed in a freezer compartment. There is the effect of evaporation mentioned above, and also the thermal contact with the freezer shelf will cool the bottom part of the body of water. If water is cold enough, close to four degrees C (the temperature at which water is densest), then near-freezing water at the bottom will rise to the top. Convection currents will continue until the entire body of water is 0 degrees C, at which point all the water finally freezes. If the water is initially hot, cooled water at the bottom is denser than the hot water at the top, so no convection will occur and the bottom part will start freezing while the top is still warm. This effect, combined with the evaporation effect, may make hot water freeze faster than cold water in some cases. In this case, of course, the freezer will have worked harder during the given amount of time, extracting more heat from hot water.” (Source).

So, the answer is both yes and no, true and false, which is a bit unusual for our Eddy IQ fun.

Thanks for playing our Eddy IQ game, and tune in again on Thursday on our Facebook page to play.

About Eddy Home
Founded in 2014, Eddy Home is an industry leader in leak protection and water visibility solutions. Our suite of smart products offers a comprehensive water management system for homeowners that protects, controls, and conserves. Our products have saved thousands of customers millions of litres of water by continuously monitoring water usage in their home, and if something unusual is detected, alerting them to the issue. For more details, please contact us at 1 877 388 3339 or email info@eddyhome.com.