Re: [Phys-l] glassware needed

[Hugh Haskell <hhaskell@mindspring.com>]

At 12:34  -0500 12/29/08, Anthony Lapinski wrote:
> I want to do a lab activity using a small immersion heater and a beaker of
> water. However, our beakers all have the usual sloped tops with a spout.
> The clip on the immersion heater is meant for a coffee cup with straight
> sides, and does not secure well to the beaker. It will fit on a tall
> graduated cylinder, but then it is difficult to mix the water to get a
> good temperature readings.
>
> So I am looking for a straight sided beaker (graduated if available) to do
> this experiment. I searched unsuccessfully on the interned, but only found
> straight sided plastic beakers and jars. Nothing made of glass and
> graduated.
Don't know about straight-sided beakers, but if you end up having to 
use the tall graduated cylinders, you might try using the magnetic 
stirrers that the chemists like (hot plate--which can be set to zero 
heat--with a rotating magnet beneath the heating element which causes 
a little magnet in the liquid container to spin and mix the liquid) 
to keep the temperature fairly uniform.

BTW, I have tried experiments using those immersion heaters in the 
past and found that the heat losses through the walls of the 
container as well as the liquid surface are so large that it is hard 
to get very reliable results. I hope you have a better plan than I 
did to minimize extraneous heat losses.

Hugh
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<mailto:hhaskell@mindspring.com>

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