re: Hot water from the tap, do you use it to cook?

quote:

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I once worked with a guy who swore that putting hot water in an ice cube tray would freeze faster than cold tap water.

I looked at this idiot like he had 2 heads, and both of them were on backwards.

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He is actually almost right and might be what the science teacher in question was really talking about.

IIRC the break over is 140F. Water at or warmer than ~140F actually freezes slower than 212F water. It is a result of rapid vaporization at higher temperatures. There are a lot of caveats like it is more pronounced with larger (but equal) surface areas. I am too lazy to go into a full explanation but should be an easy google search. If you have ever seen the videos of people in super cold areas throwing hot water into the air and it freezing immediately you have seen this effect.

Again to the guy this is a response to cold water always take longer to heat with mass, surface area, conductivity, heat introduced, and etc. There is no chicanery going up like there can be coming down.