The slower you heat tea up...the longer it stays hot...

[Samurai Jack]

Yeah, if you're waiting for the water to boil and you have it set on "warm", then it could take all day for the pot to boil, which would technically mean that it's hot for a longer period of time than if you you had set it on "high".

Them Old Chinese guys are tricky sometimes. Who knows what he meant? Maybe he was just trying to explain how to keep your tea hot in between drinking sessions.

Which reminds me, I really should start POSTING between drinking sessions.

[Toby]

Originally posted by mickey
I remember hearing someone say that microwaved food cools off faster. Maybe there is some truth to the statement.

Maybe. I think that's probably due to microwaves heating food unevenly.

The old guy's comment is crap. Two equal volumes of water both containing the same amount of heat will cool at the same rate given equal pressure and ambient temperature conditions. If both volumes are boiling before the heat source is taken away, then both will be at the same temperature and contain equal heat capacity. You can't get the water hotter than boiling because it'll change state*.

*You can get it hotter than boiling point by superheating, interestingly in a microwave. But that'd be heating the tea up quicker . Or you could change ambient conditions, i.e. atmospheric pressure and temperature. Maybe the old guy means if you heat it long enough ambient temperature will go up and therefore heat loss will be slower .

[IronFist]

Originally posted by Toby
*You can get it hotter than boiling point by superheating, interestingly in a microwave.

Yeah, and then it blows up in your face when you try to stir it (did you see those stories on the news?)

[Toby]

Yeah, I've only managed to do it once, but I knew what to expect and I was careful. I was trying to do it.

[IronFist]

You need to use a container that is perfectly smooth, right? Because don't little bumps in the sides initiate the boiling action?

Do you know at what temperature it becomes "superheated?"

[Toby]

Originally posted by IronFist
You need to use a container that is perfectly smooth, right? Because don't little bumps in the sides initiate the boiling action?

Yeah. Forget what I used. It also helps if you remove the spinning plate and set the vessel down so it's not moving .

Originally posted by IronFist
Do you know at what temperature it becomes "superheated?"

Anything over 373.135K .

[Ford Prefect]

Perhaps the extra time it takes for him to heat the tea slowly allows him a moment to go get a thermace or other insulated container...

[fa_jing]

Right, at standard atmospheric pressure water turns to steam at 100C. There is an energy expenditure associated with heating it to the boiling point, then a sizeable additional energy expenditure required to convert the boiling water into steam. The more heat you apply to the water once it reaches the boiling point, the more water is converted to steam, but the water stays at 100C until all of it is converted. Steam, on the other hand, can be raised past the 100C temperature.

Now, what is "superheating?"

[fa_jing]

http://www.phys.unsw.edu.au/~jw/superheating.html

nevermind