From: Lucila Molina (lucilaf@sbcglobal.net)
Date: Tue May 10 2005 - 10:28:37 PDT
From: "Lucila Molina" <lucilaf@sbcglobal.net> Subject: RE: Pinhole Digest #1749 - 05/10/05 Date: Tue, 10 May 2005 10:28:37 -0700 Message-ID: <auto-000001392591@exploratorium.edu>
Algis,
I am planning to make ziploc icecream with my students.
Do you have activities or the theory about colligiative, properties-
freezing point depression for this lesson?
I am sure we'll enjoy Ziploc icecream in our class.
Thanks for sharing!
Algis Sodonis
The Urban School of SF
-----Original Message-----
From: pinhole@exploratorium.edu [mailto:pinhole@exploratorium.edu]
Sent: Tuesday, May 10, 2005 12:20 AM
To: Pinhole Listserv
Subject: Pinhole Digest #1749 - 05/10/05
Pinhole Digest #1749 - Tuesday, May 10, 2005
Fuel Cell Gadget...
by <SFPhysics@aol.com>
Re: fun chem labs
by "Marc Kossover" <zeke_kossover@yahoo.com>
Anybody teaching bridge engineering?
by "Exploratorium Learning Studio" <studio@exploratorium.edu>
Re: pinhole fun chem labs
by "Algis Sodonis" <asodonis@urbanschool.org>
----------------------------------------------------------------------
Subject: Fuel Cell Gadget...
From: <SFPhysics@aol.com>
Date: Mon, 9 May 2005 05:36:28 EDT
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Greeting Geoff:
The classic fuel cell uses Hydrogen gas and Oxygen gas on each side of a
membrane catalyst to obtain power when the two gases combine to make water.
The
energy comes from the chemical bonding. The water "fuel cell" being sold
is
nothing more than a dry zinc/copper cell that activates when water is added
to make the electrolyte solution in the ammonium chloride blotter paper
separator. After several refills of water the clock dies because one of
the
electrodes or the electrolyte is used up. There are variations of this
chemical
voltaic cell and every one claims you get free energy from water. Since
water
has no more chemical energy to give up, it is not the source of power for
these novelty items but they make you think you are getting something for
nothing. Chalk up another one for marketing triumphing over the laws of
science.
Al Sefl
Who is hard at work on a zero point energy source...
And once he gets it he'll use his Tesla transmitter to send free power
around the world...
Now if only he could get beyond the zero point on his checking account...
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<DIV>Greeting Geoff:</DIV>
<DIV> </DIV>
<DIV>The classic fuel cell uses Hydrogen gas and Oxygen gas on each side
of=20=
a=20
membrane catalyst to obtain power when the two gases combine to make=20
water. The energy comes from the chemical bonding. The water
"fu=
el=20
cell" being sold is nothing more than a dry zinc/copper cell that
activ=
ates=20
when water is added to make the electrolyte solution in the ammonium
chlorid=
e=20
blotter paper separator. After several refills of water the clock
dies=
=20
because one of the electrodes or the electrolyte is used up.
Ther=
e=20
are variations of this chemical voltaic cell and every one claims you get
fr=
ee=20
energy from water. Since water has no more chemical energy to give
up,=
it=20
is not the source of power for these novelty items but they make you think
y=
ou=20
are getting something for nothing. Chalk up another one for
marketing=20
triumphing over the laws of science.</DIV>
<DIV> </DIV>
<DIV>Al Sefl</DIV>
<DIV>Who is hard at work on a zero point energy source...</DIV>
<DIV>And once he gets it he'll use his Tesla transmitter to send free
power=20
around the world...</DIV>
<DIV> </DIV>
<DIV>Now if only he could get beyond the zero point on his checking=20
account...</DIV>
<DIV> </DIV></FONT></FONT></FONT></BODY></HTML>
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Subject: Re: fun chem labs
From: "Marc Kossover" <zeke_kossover@yahoo.com>
Date: Mon, 9 May 2005 07:23:11 -0700 (PDT)
From: Marc Crown <mcrown@gatewayhigh.org>
Subject: fun chem labs
Date: Sun, 8 May 2005 14:20:39 -0700
> something that will send em off with a desire to
take
> more chemistry.
Do you have hot plates and some clean labwear or pots
and pans of your own? If so, the chemistry of cooking
can be a blast. I've taught this off and on to adults
and children for years.
The way to make this scientific, though, is to give
different recipes to the different groups in class and
have them compare the results after they are done.
That way they can see what's happening.
You might want to start with simple candies. You can,
for example, add water to granulated sugar (sucrose)
to make syrup and then evaporate the water back out
again to make sugar (sucrose) crystals. If you add a
10 mL of corn syrup (nearly pure fructose) to a 250 mL
of sucrose, it will never re-crystallize; however, and
brown into carmel. Why? The fructose is not the same
shape as sucrose and interfers with crystal formation.
That means that the water keeps evaporating until the
solution gets so hot that the sucrose starts to brown.
Serve over ice cream, which as another person has
pointed out has several bits of useful chemistry
involved. Not just freezing point depression necessary
to freeze the water, but kneading and aerating the
mixture to keep the crystals small the product less
dense.
Making fudge falls into the same crystallization
problem. Fudge is primarily sugar and fat with a bit
of chocolate (or other) flavoring. You want many small
sugar crystals to make the candy soft and creamy
feeling. Once everything is melted and combined, you
want to cool it gentle at first so that many crystals
are formed, then you want to beat it hard to keep the
crystals from growing. Fudge made with marshmallow
cream works because it includes fructose in the
marshmallow cream and stabilizers (like gelatin) to
hold the fudge together even without good crystals.
If you'd like more ideas, even ones that aren't candy,
just drop me a line.
Resources:
Cookwise: The Hows and Whys of Successful Cooking by
Shirley O. Corriher
On Food and Cooking: The Science and Lore of the
Kitchen by Harold McGee
<http://www.exploratorium.edu/cooking/index.html>
Marc "Zeke" Kossover
The Jewish Community High School of the Bay
San Francisco, CA 94121
<http://tochnit.jchsofthebay.org/~zkossover>
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
----------------------------------------------------------------------
Subject: Anybody teaching bridge engineering?
From: "Exploratorium Learning Studio" <studio@exploratorium.edu>
Date: Mon, 9 May 2005 15:54:24 -0700 (PDT)
Two good articles in the latest batch of magazines. Technology Teacher's
cover story is a feature on "teaching elements and principles of bridge
design" (unfortunately, with no identification of the bridge in the
photo). And American Scientist has a fine historical article on the
Joshua A. Norton (a/k/a "Bay") Bridge, including the controversy and
science of the alternative designs. (Bonus: cover story is on the physics
of pitching fastballs.)
We have books, yes, but don't forget the magazines.
Jo Falcon, MLIS
===============================================================
Exploratorium Learning Studio
3601 Lyon Street
San Francisco, CA 94123
(Phone) 415-561-0343
(Fax) 415-561-0370
(Email) studio@exploratorium.edu
(URL) http://www.exploratorium.edu/ls
===============================================================
----------------------------------------------------------------------
Subject: Re: pinhole fun chem labs
From: "Algis Sodonis" <asodonis@urbanschool.org>
Date: Mon, 09 May 2005 20:13:54 -0700
This is a multi-part message in MIME format.
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A real winner is making ziploc icecream
this is a lesson on colligiative properties- freezing point depression.
In a large ziploc bag, mix ice and salt (ordinary table salt works well,
since it dissolves quickly)
In another smaller ziploc bag, about 1 cup milk, 1 teaspooon coffee creamer
a few teaspoons sugar and some vanilla extract to taste
additional stir-ins can be optional.
place the smaller sealed bag into the larger one with ice/salt mixture and
seal the larger bag. Start mixing everything (gloves can be helpful here).
Within about 15-20 minutes, this will start to harden. It tastes
surprisingly good.
Algis Sodonis
The Urban School of SF
"Pinhole Listserv" <pinhole@exploratorium.edu> on Sunday, May 8, 2005 at
2:20 PM -0800 wrote:
>I left myself a week at the end of the quarter to do some "just for
>fun" labs in my chemistry class. I was thinking along the lines of some
>polymer stuff but haven't come across anything that appealing. does
>anyone have any good suggestions that they've done in the past?
>Doesn't have to be polymer, can be from any unit/ any experiment or
>demo, but something that will send em off with a desire to take more
>chemistry.
>
>I've never had "free" time before.
>thanks
>marc
>
>
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>To subscribe to the digest and only get 1 combined message a day, send an
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Content-Transfer-Encoding: quoted-printable
<=21DOCTYPE HTML PUBLIC =22-//W3C//DTD HTML 4.0 Transitional//EN=22>
<html><head><meta http-equiv=3D=22Content-Type=22 content=3D=22text/html; c=
harset=3DISO-8859-1=22>
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<font face=3D=22Geneva=22 size=3D=22+0=22 color=3D=22=23000000=22 style=3D=
=22font-family:Geneva;font-size:10pt;color:=23000000;=22>A real winner is m=
aking ziploc icecream <br>
<br>
this is a lesson on colligiative properties- freezing point depression.<br>
<br>
In a large ziploc bag, mix ice and salt (ordinary table salt works well, si=
nce it dissolves quickly)<br>
<br>
In another smaller ziploc bag, about 1 cup milk, 1 teaspooon coffee creamer=
a few teaspoons sugar and some vanilla extract to taste<br>
additional stir-ins can be optional. <br>
<br>
place the smaller sealed bag into the larger one with ice/salt mixture and =
seal the larger bag. Start mixing everything (gloves can be helpful h=
ere). Within about 15-20 minutes, this will start to harden. It=
tastes surprisingly good.<br>
<br>
Algis Sodonis<br>
<br>
The Urban School of SF<br>
<br>
<br>
<b>"Pinhole Listserv" <<a href=3D=22mailto:pinhole=40explorato=
rium.edu=22>pinhole=40exploratorium.edu</a>> on Sunday, May 8, 2005 at 2=
:20 PM -0800 wrote:<br>
</b></font><span style=3D=22background-color:=23d0d0d0=22><font face=3D=22G=
eneva=22 size=3D=22+0=22 color=3D=22=23000000=22 style=3D=22font-family:Gen=
eva;font-size:12pt;color:=23000000;=22>I left myself a week at the end of t=
he quarter to do some "just for <br>
fun" labs in my chemistry class. I was thinking along the lines of som=
e <br>
polymer stuff but haven't come across anything that appealing. does <br>
anyone have any good suggestions that they've done in the past? <br>
Doesn't have to be polymer, can be from any unit/ any experiment or <br>
demo, but something that will send em off with a desire to take more <br>
chemistry.<br>
<br>
I've never had "free" time before.<br>
thanks<br>
marc<br>
<br>
<br>
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