Re: pinhole Salting water

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From: Gene Thompson (gthompso@ccsf.cc.ca.us)
Date: Wed Dec 06 2000 - 18:23:17 PST 

Date: Wed, 6 Dec 2000 18:23:17 -0800 (PST)
From: Gene Thompson <gthompso@ccsf.cc.ca.us>
Subject: Re: pinhole Salting water
Message-ID: <Pine.HPX.4.21.0012061819290.16107-100000@fog.ccsf.cc.ca.us>

There's a fun one you can do as a lab (as a cookbook style lab it's a
blast because they don't know what to expect -- I don't tell them), or you
can do it in a restaurant you plan on never returning to. Put a little
puddle of fresh water on the table. Put a beaker (or glass) of crushed
ice with a little water and a LOT of salt in it. Be careful not to spill
salt in the puddle. Then hole the rim so the beaker (glass) doesn't move
while you stir, stir, stir, stir. Restaurant knives are good for
stirring. The glass quickly gets cold, frost forms at the base, and in
about 5 minutes max you can't move the glass (oops, beaker) because it's
frozen to the table.

I caused my family great grief when we went out to dinner.

Ellen Koivisto
George Washington High School, SF

On Wed, 6 Dec 2000 CGDonahoe3@aol.com wrote:

> supposedly, adding salt to water raises the boiling temperature---thereby the
> water absorbs more heat than pure water at 100 C.
>
> conversely, adding salt to water will lower its freezing temperature---why
> salt is spread on roads to lower freezing temperature to keep vehicles from
> sliding on ice.
>
> How to prove? Heat two beakers, one plain and one heavily salted and
> measure temperature peak. Fresh = 100 c, salt water is greater.
>
> on the back side, have two beakers of heavily iced water, fresh measures at
> about 0 C and salt water will go below -10C
>
> Easy to do with proper safety precautions.
>
> respectfully,
>
> cgd3
>
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