From: Geoff Ruth (gruth@leadershiphigh.org)
Date: Wed May 11 2005 - 07:08:08 PDT
Message-Id: <p06110416bea6d3d85e65@[192.168.1.149]> Date: Wed, 11 May 2005 07:08:08 -0700 From: Geoff Ruth <gruth@leadershiphigh.org> Subject: boiling pt elevation
Lucila,
I do a lab related to freezing pt depression that focuses on boiling
point elevation. I actually do this with my AP chem class, but it
could be modified for some first year chem classes (it's one of the
easiest AP labs.)
I ask students to find out the temperature at which the coolant in my
car's radiator will freeze at.
(I don't use the actual coolant, but rather a simulation (with green
food coloring) since ethylene glycol is toxic.) In AP, I then have
them think of a procedure they could use to figure out its freezing
point. For a first year chem class, you could guide them towards
realizing that if they measure the boiling point elevation of the
solution, then they can calculate the solution's molality, and then
use that to figure out the freezing point depression of water. By
doing this, they connect boiling pt elevation with freezing pt
depression.
Or if this is too complex (it would be for my 1st year chem kids),
you could do a more qualitative lab by giving them solutions with
differing amounts of solute dissolved in the same solvent, and then
having them find the bp of each solution. By comparing, they should
be able to see that the more solute, the higher the bp. Here in the
bay area, you might relate it to evaporating water from a salt pond
and how the time to evaporate the next x mL of water increases as the
pond becomes increasingly salty.
I used to hate teaching colligative properties, but I now think
they're cool because there are a lot of easy-to-see and
easy-to-experience real-world consequences.
- Geoff
>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
>
>
>-------------------------------1115631387
>Content-Type: text/plain; charset="US-ASCII"
>Content-Transfer-Encoding: 7bit
>
>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...
>
>
>-------------------------------1115631387
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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>
>
>-------------------------------1115631387--
>
>----------------------------------------------------------------------
>
>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.
>
>----=_--00867969.0086790e.bea5d772
>Content-Type: text/plain; charset=ISO-8859-1
>Content-Transfer-Encoding: 8bit
>
>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
>>
>>
>>---------------------------------------------------------------------------
>>
>>To unsubscribe from pinhole, send an email to requests@exploratorium.edu
>>with the words 'unsubscribe pinhole' (without the quotes) in the SUBJECT
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>>
>>To subscribe to the digest and only get 1 combined message a day, send an
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>>---------------------------------------------------------------------------
>>
>>
>
>
>
>----=_--00867969.0086790e.bea5d772
>Content-Type: text/html; charset=ISO-8859-1
>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>
><style type=3D=22text/css=22>body=7Bmargin-left:10px;margin-right:10px;marg=
>in-top:0px;margin-bottom:0px;=7D</style>
></head>
><body marginleft=3D=2210=22 marginright=3D=2210=22 margintop=3D=220=22 marg=
>inbottom=3D=220=22>
><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>
>---------------------------------------------------------------------------=
><br>
><br>
>To unsubscribe from pinhole, send an email to <a href=3D=22mailto:requests=
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