Is it true hot water freezes quicker than cold water?
Hot water takes longer to cool down than cold water, BUT if you start with equal amounts of hot and cold water, the hot water will lose a lot of water through evaporation, which cools the water more quickly, and means there is less water to cool down. In that case, the hot water can freeze faster than the cold. But if you made 1 gram of ice from cold water, and 1 gram of ice from hot water, the cold would freeze first.
Water starts to freeze at 0 degrees C. Pour some liquid nitrogen on the hot water, and set the cold water outside on a cool day, and sure enough, your hot water froze first. Reverse it, and the cold water freezes first. But if you put both in a freezer, I would have to lean to say the colder water would freeze first, because for the water to freeze it would have to lose the heat it has in it already. The hotter water has more heat and therefor would seem to me to have to take longer to move the heat. That is assuming that heat transfer is linear, but even if it’s not, the only other option I can think of is that they would both freeze at the same time, because the hot water would have to reach a point where it is the same temperture as what the cold water was at previously.
This is a common myth. Hot water cannot possibly freeze faster than cold water, because it has to go through the stage of being cold water on its route to turning into ice. It is possible, in very cold weather, for the vapour from hot water in a partly filled container to form frost higher up the container quite quickly, which may be where this myth comes from.
