Date: Wed Dec 31 02:10:31 2008

Author: Dan Bernoulli

Subject: Re: glassware needed

Post:

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I forgot to add=2C a styrofoam cup actually works pretty well if you know w=
hat you are doing. One can easily mark a scale on the cup. If you are a stu=
dent=2C you generally don't realize just how much you should be stirring in=
order to keep the temperature in the medium constant - especially when mel=
ting ice. It is difficult (but not absolutely impossible) to melt a hole in=
the cup as long as there is ample water (that isn't too hot).=20

We now do the lab in home made pots (we call them slush buckets) made of 6 =
in id pvc pipe with power resistors mounted on the outside of the aluminum =
bottoms. After showing students the resistors are equivalent to a 100 watt =
light bulb we have them touch the resistors while the heaters are on=2C hea=
ting the water. They are surprised to find they stay quite cool. One doesn'=
t necessarily need high temperatures to transfer lots of energy.

If you do measure heat of fusion=2C do some calculations to figure out how =
long it will take to melt the ice. With a liter of ice at 0C it could take =
most of a lab period just to melt the ice. It is a boring but effective way=
to emphasize just how much energy it takes to change ice to water compared=
to the energy it takes to raise the temperature of the same mass of water =
from 0C to say 100C.=20

Dan Beeker

> Date: Mon=2C 29 Dec 2008 12:34:26 -0500
> Subject: [tap-l] glassware needed
> To: tap-l@lists.ncsu.edu=3B phys-l@carnot.physics.buffalo.edu
> From: Anthony_Lapinski@pds.org
>=20
> Happy holidays everyone!
>=20
> I want to do a lab activity using a small immersion heater and a beaker o=
f
> water. However=2C 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=2C and does not secure well to the beaker. It will fit on a tall
> graduated cylinder=2C but then it is difficult to mix the water to get a
>=20
> So I am looking for a straight sided beaker (graduated if available) to d=
o
> this experiment. I searched unsuccessfully on the interned=2C but only fo=
und
> straight sided plastic beakers and jars. Nothing made of glass and
>=20
> Does anybody know of a source/company for what I need? Thanks!
>=20

_________________________________________________________________
It=92s the same Hotmail=AE. If by =93same=94 you mean up to 70% faster.
1_122008=

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Content-Type: text/html; charset="Windows-1252"
Content-Transfer-Encoding: quoted-printable

I forgot to add=2C a styrofoam cup actually works pretty well if you know w=
hat you are doing. One can easily mark a scale on the cup. If you are a stu=
dent=2C you generally don't realize just how much you should be stirring in=
order to keep the temperature in the medium constant - especially when mel=
ting ice. It is difficult (but not absolutely impossible) to melt a hole in=
the cup as long as there is ample water (that isn't too hot). We n=
ow do the lab in home made pots (we call them slush buckets) made of 6 in i=
d pvc pipe with power resistors mounted on the outside of the aluminum bott=
oms. After showing students the resistors are equivalent to a 100 watt ligh=
t bulb we have them touch the resistors while the heaters are on=2C heating=
the water. They are surprised to find they stay quite cool. One doesn't ne=
cessarily need high temperatures to transfer lots of energy.If you =
do measure heat of fusion=2C do some calculations to figure out how long it=
will take to melt the ice. With a liter of ice at 0C it could take most of=
a lab period just to melt the ice. It is a boring but effective way to emp=
hasize just how much energy it takes to change ice to water compared to the=
energy it takes to raise the temperature of the same mass of water from 0C=
to say 100C. Dan Beeker>=3B Date: Mon=2C 29 Dec 2008 12:=
34:26 -0500>=3B Subject: [tap-l] glassware needed>=3B To: tap-l=
@lists.ncsu.edu=3B phys-l@carnot.physics.buffalo.edu>=3B From: Anthon=
y_Lapinski@pds.org>=3B >=3B Happy holidays everyone!>=3B =
>=3B I want to do a lab activity using a small immersion heater and a=
beaker of>=3B water. However=2C our beakers all have the usual slope=
d tops with a spout.>=3B The clip on the immersion heater is meant fo=
r a coffee cup with straight>=3B sides=2C and does not secure well to=
the beaker. It will fit on a tall>=3B graduated cylinder=2C but then=
it is difficult to mix the water to get a>=3B good temperature readi=
ngs.>=3B >=3B So I am looking for a straight sided beaker (grad=
uated if available) to do>=3B this experiment. I searched unsuccessfu=
lly on the interned=2C but only found>=3B straight sided plastic beak=