From: Joe Leet (jleet@prodigy.net)
Date: Mon Dec 23 2002 - 09:15:33 PST
Message-ID: <00a701c2aaa6$e8061140$cdb23b41@preferred-user> From: "Joe Leet" <jleet@prodigy.net> Subject: Re: Pinhole Digest #1091 - 12/19/02 Date: Mon, 23 Dec 2002 09:15:33 -0800
Hello,
Just curious--those of you that use the "grain elevator" in their classroom,
what curriculum is this supporting?--Combustion???
Thank you for the great idea.
Joe
-----Original Message-----
From: Pinhole Listserv <pinhole@exploratorium.edu>
To: Pinhole Listserv <pinhole@exploratorium.edu>
Date: Wednesday, December 18, 2002 11:21 PM
Subject: Pinhole Digest #1091 - 12/19/02
Pinhole Digest #1091 - Thursday, December 19, 2002
Re: grain elevator and questions
by "Ronald Wong" <ronwong@inreach.com>
salt and water's freezing point
by "Meghan Nolan" <meghan_nolan@yahoo.com>
Re: pinhole salt and water's freezing point
by "Geoff Ruth" <gruth@leadershiphigh.org>
Re: grain elevator and questions
by "Roy Mayeda" <roy_mayeda@isd743.k12.mn.us>
Re: Sublimation
by "Marc Afifi" <marc_afifi@yahoo.com>
grain elevator
by "Craig Childress" <craigchildress@hotmail.com>
Re: pinhole Re: grain elevator and questions
by "Paul Doherty" <pauld@exploratorium.edu>
Re: pinhole salt and water's freezing point
by "Paul Doherty" <pauld@exploratorium.edu>
Re: pinhole grain elevator and questions
by "Tory Brady" <toryb@exploratorium.edu>
Sublimation
by "Sue Lowder" <sdlowder@yahoo.com>
Fwd: iCademy Awards
by "Deb Hunt" <dhunt@exploratorium.edu>
----------------------------------------------------------------------
Subject: Re: grain elevator and questions
From: "Ronald Wong" <ronwong@inreach.com>
Date: Wed, 18 Dec 2002 02:03:50 -0800
A few "common" examples to add to Paul's list:
Mike Schulist asked:
>2. "do other substances sublimate besides dry ice?"
Mothballs (naphthalene).
Just like a puddle of water on the sidewalk can evaporate and turn into a
gas even though it's below the boiling point, a solid can sublime into a
gas even though it's below the sublimation point (but at a far slower
rate).
Have you ever wondered what happened to the ice cubes in the ice-tray that
were sitting untouched in the freezer of your frost-free refrigerator for
ages? They sublimed into the air.
>3. "Is plasma a higher energy state than a gas? Where else does
plasma exist besides the outer atmoshpere and in fires?
Anytime you have an ionized gas, you have a plasma. So neon signs,
fluorescent tubes (where the plasma produces the UV that is then converted
into visible light by the fluorescent coating), bolts of lightning, the arc
produced during arc welding (or by students who short out an electrical
circuit), as well as those novelty items that consist of a sphere with
glowing streamers moving around in them which respond when you touch the
surface of the sphere with your hand/fingers (the Exploratorium has an
beautiful piece of artwork that works on the same principle) are additional
examples of where plasmas can be found.
ron
----------------------------------------------------------------------
Subject: salt and water's freezing point
From: "Meghan Nolan" <meghan_nolan@yahoo.com>
Date: Wed, 18 Dec 2002 04:14:09 -0800 (PST)
Quick question...
Does anyone have a good explanation (for a curious
group of 8th graders...and their teacher) for why salt
lowers the freezing point of water?
Thanks in advance!
Meghan
----------------------------------------------------------------------
Subject: Re: pinhole salt and water's freezing point
From: "Geoff Ruth" <gruth@leadershiphigh.org>
Date: Wed, 18 Dec 2002 07:43:15 -0800
The salt particles get in between the H2O molecules and prevent them
from bonding with one another in an ice crystal. The more salt you
add to water, the more salt there is to prevent water molecules from
linking together, and the lower the freezing point of the mixture.
In other words, the sodium and chloride ions disrupt the hydrogen
bonding that occurs between the water molecules.
At least, that's my take on it
>Quick question...
>
>Does anyone have a good explanation (for a curious
>group of 8th graders...and their teacher) for why salt
>lowers the freezing point of water?
>
>Thanks in advance!
>Meghan
>
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>---------------------------------------------------------------------------
----------------------------------------------------------------------
Subject: Re: grain elevator and questions
From: "Roy Mayeda" <roy_mayeda@isd743.k12.mn.us>
Date: 18 Dec 2002 10:47:47 -0600
Mike,
There's a nice demo of this on the NOVA "Kaboom" video. They show
sprinkling a bit of flour into a section of heavy cardboard tubing (probably
5-6 feet long and 3-4 inches in diameter) with a candle at the bottom. The
demonstrator seemed to rapidly tap small amounts into the tube to get the
mixing effect Paul was talking about. Even though lycopodium powder is
plant material, I guess it seems more like the grain elevator if you use
flour. (What's really odd about the elevators I see out here is all the
huge piles of soybeans and corn that sit outside in the dirt lots around the
elevator until they can be shipped!)
About the sublimation thing -- I think water will also do this in the
freezer, yes? Not sure about that (whether it sublimates or melts first).
Seemed to me that if you leave ice cubes in the freezer a long time, they
keep decreasing in size. Also, I think the term "deposition" was also used
for the state change from gas directly to solid, though I also use
"sublimation" for both processes sometimes as well. I think both were
acceptable last time I looked it up.
Good luck.
Roy Mayeda
Sauk Centre HS
Sauk Centre, MN
----------------------------------------------------------------------
Subject: Re: Sublimation
From: "Marc Afifi" <marc_afifi@yahoo.com>
Date: Wed, 18 Dec 2002 09:07:00 -0800 (PST)
Paul D calls the gas to solid transition sublimation.
This is how scientists refer to the transition but it
is a bit confusing to students who like to have
different terms for different phase transitions. I use
the term deposition to refer to the change from gas to
solid but I advise the students that the term
sublimation really refers to both.
Also, water sublimates here on Earth, too. If you
leave a tray of ice cubes in the freezer for a long
time you'll notice that the cubes get smaller and
smaller as time passes. This is because ice has an
appreciable vapor pressure. In fact, under the right
conditions, many, many substances will sublimate. I
hesitate to say all because in chemistry there is
usually an exception to every "rule." You can find
more information about specific substances by looking
at their phase diagrams.
Melting only occurs within a specific range of
temperature-pressure combinations for any particular
substance. The reason ice will not melt on mars is
that the atmospheric pressure is too low to support
the formation of a liquid. The reason that ice will
not melt in your freezer is that the temperature is
too low. Ice can be made to melt at below zero
temperatures if the pressure is high enough.
One of my favorite demonstrations is the formation of
liquid carbon dioxide. This is done by taking crushed
dry ice and putting it into a clear, strong, pressure
release protected, sealable plastic tube. As the dry
ice sublimates the pressure in the tube eventually
reaches a high enough value that the dry ice melts.
Opening the tube releases the pressure and the dry ice
reappears as the fastest molecules escape leaving the
slowest ones behind. It's a very cool demo...pardon
the pun.
I hope this helps and doesn't confuse, but as Paul D
always says...it's more complicated than that.
Happy holidays! You've earned this vacation.
-M
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----------------------------------------------------------------------
Subject: grain elevator
From: "Craig Childress" <craigchildress@hotmail.com>
Date: Wed, 18 Dec 2002 10:22:46 -0800
I use baking flour and a sifter about a foot above the tube opening.
Incidentally, I use a six foot section of six inch diameter PVC with two
candles. This setup develops a "ball of fire" around five feet in diameter
above the tube.
Craig Childress
Industrial Technology Instructor
Hillsdale High School
(650) 378-8170 x226
(650) 574-4173 FAX
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----------------------------------------------------------------------
Subject: Re: pinhole Re: grain elevator and questions
From: "Paul Doherty" <pauld@exploratorium.edu>
Date: Wed, 18 Dec 2002 09:44:33 -0800
Note
The Exploratorium used to have a beatiful plasma artwork named "Quiet
Lightning"
A basketball sized glass sphere with plasma arcs inside it that responded
to the presence of human conductors.
This summer on a hot day the glass imploded with a whomp.
No one was near the exhibit at the time.
Summer institute teachers rushed to the scene of the explosion and kept
visitors away from the glass and high voltage until the Exploratorium clean
up team arrived.
This was one of the first plasma spheres ever made. The exhibit was
developed by Artist in Residence Bill Parker at the Exploratorium.
We put the word out to other museums to watch out for catastrophic failure
of their plasma spheres.
Paul D
----------------------------------------------------------------------
Subject: Re: pinhole salt and water's freezing point
From: "Paul Doherty" <pauld@exploratorium.edu>
Date: Wed, 18 Dec 2002 09:51:43 -0800
>Quick question...
>
>Does anyone have a good explanation (for a curious
>group of 8th graders...and their teacher) for why salt
>lowers the freezing point of water?
>
>Thanks in advance!
>Meghan
>
Hi Meghan
It's a dance.
At the surface of an ice cube in liquid water, water molecules are always
leaving the ice to become liquid and also leaving the liquid to add to the
ice.
At temperatures above 0 C the water molecules leaving the ice predominate
and the ice melts. At temperatures below 0 C the molecules adding to the
ice are more numerous.
The presence of salt or any other solute (like sugar) gets in the way of
the water molecules trying to go from liquid to solid more than they get in
the way of water molecules leaving the solid. This changes the balance
between freezing and thawing so that the equilibrium happens at a lower
temperature.
Paul Doherty
>---------------------------------------------------------------------------
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>To subscribe to the digest and only get 1 combined message a day, send an
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>---------------------------------------------------------------------------
----------------------------------------------------------------------
Subject: Re: pinhole grain elevator and questions
From: "Tory Brady" <toryb@exploratorium.edu>
Date: Wed, 18 Dec 2002 15:17:59 -0800
>Hi Mike
>
>Don't forget to mix air into the powder by blowing it into the top of the
>chamber. Don't sprinkle it in.
>
>1. Carbon dioxide goes directly from solid to gas (sublimation)
>and also from gas to solid (also sublimation)
>
>2. Iodine also sublimates at room temprarture.
>Water sublimates on Mars.
>
>3. Plasma is a higher energy state than gas.
>The sun and other stars are plasmas.
>The solar wind is a plasma.
>Inside the pixels of modern flat screen plasma televisions there is a ...
>
>Paul D
>
>
>
>
>> Last summer in the alumni chemistry class, we built "grain elevator"
>> tubes. The plastic tubes stand upright and a candle sits on the
>> bottom. The idea is to put powder substances in the tube and see
>> them ignite. I'm having trouble remembering exactly how this worked.
>> I bought Lycopodium, and my first few attempts produced nothing.
>> Then, I dumped teaspoon on the flame, and it was a great fire effect,
>> but the powder got all over everything and it left a huge mess. I
>> also remember being able to put other poweders in the tube and seeing
>> them ignite. So far, everything either does nothing or just puts out
>> the flame. I seem to recall this was a more "graceful" and easy to
>> perform experiment. Does anyone know how to get the maximum benefit
>> from this tube? Is there a way to make corn starch and flour light
>> into a nice fire?
>>
>> Also, my students asked some questions today that I said I'd "research."
>> 1. "does the carbon dioxide in dry ice go directly from being a gas
>> to being a solid?"
>>
>> 2. "do other substances sublimate besides dry ice?"
>>
>> 3. "Is plasma a higher energy state than a gas? Where else does
>> plasma exist besides the outer atmoshpere and in fires?
>>
>> Thanks for your help!
>>
>> -Mike Schulist
>> Miller Creek Middle School
>>
>> -------------------------------------------------------------------------
-- >> >> To unsubscribe from pinhole, send an email to requests@exploratorium.edu >> with the words 'unsubscribe pinhole' (without the quotes) in the SUBJECT >> of the email. >> >> To subscribe to the digest and only get 1 combined message a day, send an >> email to requests@exploratorium.edu with the words 'subscribe digest >> pinhole' (without the quotes) in the SUBJECT of the email. >> >> Check out what your colleagues have written on Pinhole in the Pinhole >> archives at: http://saturn.exploratorium.edu/ti/alumni/pinhole.html >> ------------------------------------------------------------------------- -- >> >> >> > > >-------------------------------------------------- >This message was sent using Exploratorium web mail > http://www.exploratorium.edu/ > > > >--------------------------------------------------------------------------- > >To unsubscribe from pinhole, send an email to requests@exploratorium.edu >with the words 'unsubscribe pinhole' (without the quotes) in the SUBJECT >of the email. > >To subscribe to the digest and only get 1 combined message a day, send an >email to requests@exploratorium.edu with the words 'subscribe digest >pinhole' (without the quotes) in the SUBJECT of the email. > >Check out what your colleagues have written on Pinhole in the Pinhole >archives at: http://saturn.exploratorium.edu/ti/alumni/pinhole.html >-------------------------------------------------------------------------------------------------------------------------------------------------
Subject: Sublimation From: "Sue Lowder" <sdlowder@yahoo.com> Date: Wed, 18 Dec 2002 16:57:59 -0800 (PST)
--0-855255108-1040259479=:68821 Content-Type: text/plain; charset=us-ascii
Much of the snow in the Sierras sublimates.
Sue Lowder Truckee High School Truckee, California Fulbright Exchange Teacher 2001-2002
Exeter College Exeter, Devon England sdlowder@yahoo.com
--------------------------------- Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now --0-855255108-1040259479=:68821 Content-Type: text/html; charset=us-ascii
<P>Much of the snow in the Sierras sublimates. <P> </P><BR><BR><P>Sue Lowder<BR>Truckee High School<BR>Truckee, California<BR>Fulbright Exchange Teacher 2001-2002</P> <P>Exeter College<BR>Exeter, Devon England<BR>sdlowder@yahoo.com</P><p><br><hr size=1>Do you Yahoo!?<br> <a href="http://rd.yahoo.com/mail/mailsig/*http://mailplus.yahoo.com">Yahoo! Mail Plus</a> - Powerful. Affordable. <a href="http://rd.yahoo.com/mail/mailsig/*http://mailplus.yahoo.com">Sign up now</a> --0-855255108-1040259479=:68821--
----------------------------------------------------------------------
Subject: Fwd: iCademy Awards From: "Deb Hunt" <dhunt@exploratorium.edu> Date: Wed, 18 Dec 2002 18:41:36 -0800
>fyi.
Deb *** > >iCademy Awards > >Closing Date: >February 1, 2003. > >Amount: > >Eligible Applicants: >Any individual or group of students and/or teachers, K-12 through Higher Ed >can enter. > >Agency/Department: >Microcomputers in Education Conference >P.O.Box 870101 >Tempe,AZ 85287-0101 >Phone 480.965.9700 >Fax 480.965.4128 > >SUMMARY: >The iCademy Awards competition encourages educators and students to grab >cameras, iMacs and iMovie to create digital movies based on classroom >curriculum and state-accepted teaching standards. > >Listed in: > >For detailed information go to: > > > >Sheila Curtis >Development Specialist >Exploratorium >3601 Lyon Street >San Francisco, CA 94123 ><mailto:sheilac@exploratorium.edu>sheilac@exploratorium.edu >415-353-0434 phone >415-561-0307 fax
Deborah Hunt CTL Senior Information Specialist Exploratorium http://www.exploratorium.edu mailto: dhunt@exploratoriu.edu 415-353-0485 (fax) 415-561-0370
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