Re: Mpemba effect" ??

[John Barrer <forcejb@YAHOO.COM>]

Another example. I once lived in an area where many
houses had been built with skimpy insulation. On one
very cold night, I had a (hot) water line freeze and
burst. A plumber neighbor claimed that this was
"always" the case - the HW pipe would often be frozen
while the CW would be OK. I thought at the time that
maybe this was b/c some of the dissolved minerals in
the feedwater tend to be deposited on the internal
surface of the domestic water heater, but then some
calculations showed the differential effect on
freezing point depression to be awfully small. Any
other experiences with frozen pipes? John Barrere Apex
HS
--- Savinainen Antti <antti.savinainen@KUOPIO.FI>
wrote:
> James McKey wrote:
>
> > I've never heard of that name. I have heard the
> tale about hot water freezing
> > faster than cold, but do not see how that's
> possible for equal starting and
> > ending masses of water under equivalent external
> conditions.
>
> My student did an Extended Essay on the topic few
> years ago in the
> International Baccalaureate program.
> She monitored cooling and freezing of the same
> amounts of water in the same
> freezer in different kinds of containers. She used a
> computer based measurement
> of temperature. I didn't believe in the effect
> before I saw how initially
> warmer water actually did froze faster that colder
> water. The (initially)
> colder water spend more time in a super cooled state
> under 0 degrees of Celsius.
> Then the temperature raised to zero and started to
> drop again after all the
> water had frozen. This took place repeatedly for
> certain kind of containers.
> Why this happened remained a mystery.
>
> Regards,
>
> AnttI Savinainen
> Kuopio Lyseo High School/IB
> Finland


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