2007-04-29 07:35:37 · 5 answers · asked by richard n 1 in Science & Mathematics ➔ Other - Science
No, it's not true.
I saw a thing on PBS where they actually did an experiment on camera about hot vs. cold water for making ice, and cold water totally froze faster than hot.
In order for a substance to change phase (that is, go from solid to liquid to vapor or back), it has to reach certain temperatures (or you have to change the pressure or something to compensate for the fact that the temp doesn't match the usual standards.)
Hot water is closer to a vapor than a solid. Cold water is closer to a solid than a vapor. If a substance goes through the phase changes, hot water would have to go to cold, then to ice (solid).
Cold water doesn't have to take that extra step of cooling down in order to change phase. It's already close to solid.
2007-04-29 09:49:26 · answer #1 · answered by SlowClap 6 · 0⤊ 0⤋
It actually depends. This is called the Mpemba effect.
It depends a lot on the environment, where the freezing takes place, on whether the cold water you have had been hot before (has to do with dissolved gases). This has not been explained, but there are circumstances, under which hot water freezes over before cold water does.
Explanations include evaporation, insulating layers of ice forming and others. Whoever solves the mystery fully, will get much fame.
2007-04-29 17:26:47 · answer #2 · answered by misiekram 3 · 0⤊ 0⤋
You can only make ice cubes by freezing water so using cold water to begin with would be faster
2007-04-29 14:38:55 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Hot water changes temperature the fastest, but it does not become ice faster. Cold water actually makes ice faster because it is closer to freezing and does not need to change temperature as far.
2007-04-29 14:45:59 · answer #4 · answered by threedaysoff 2 · 0⤊ 0⤋
No, it's not true.
2007-04-29 14:39:17 · answer #5 · answered by Joan H 6 · 0⤊ 0⤋