Re: Water Boil Water

[brian whatcott <inet@intellisys.net>]

At 22:58 3/15/98 +0800, you wrote:
> Hi,
> ...
> We know water boils at 100 degress C.

This list provides a lively environment for people who have several 
different interests and specialities. (One is tempted to say
"Bees in their bonnets" but hastily retracts this  :-)

It is apparently a matter of record that the interest of thermodynamics
is particularly well-served here, and so one becomes increasingly careful 
about using ('bandying about') terms of the art like heat, friction,
flow, flux, work, energy, entropy, enthalpy and so on.

So now I can see that you are here in the position of walking into an
ambush - unsuspecting.
 You are undoubtedly aware of the range of temperatures over which water
may be expected to boil. Respecting your national patrimony, one could
make reference to the varying taste of tea brewed upon a high mountain, 
etc., etc.

> Suppose I have a glass bottle half-filled with water. I place this bottle
> (with no capping) into a pot of water that covers two-thirds of the 
> bottle. Now I boil this pot of water (also not covered). Will the 
> bottle of water boil?
>
> I thought it would. I did not try it out yet. But my HOD was actually
> trying out the experiment in his home when his grandmother came in 
> to the kitchen, saw what he was doing, gave him a thorough scolding, 
> and told him that the bottle of water will never boil in this way.
>
> My question is: Is she correct? If she is, what's the theory behind it?
>
> Thanks.
>
> Steven.


I fancy that your HOD's Grandparent had in mind the imperative need for a
temperature difference in order to permit the transfer of heat.
For two containers at the same temperature (that of the local boiling 
point for water) there cannot be heat transfer - so because there is 
this considerable latent heat of vaporization of water needed to trigger
'boiling' as we normally visualize it - boiling does not ensue.

 The Grandparent in question might even point out the device she keeps 
in the kitchen specifically to bring about this non-boiling result,
called 'the double boiler'.

Sincerely

Whatcott  Altus OK