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Hey all -
We do lots of kitchen chemistry experiments in our teacher workshops,
but precipitation reactions are hard to come by. However ...
1) re: Jonah's Ziploc bag demo (which I love!) - you can replace the
phenol red in this experiment if you substitute 1/8 tsp. Turmeric powder
(or curry) in a 1:3 solution of rubbing alcohol in water. This yellow
indicator will turn red when you add baking soda to it, and then turn
back to yellow when you add calcium chloride. Also - we tested quite a
few brands of road salt in this experiment, and very few of them worked
the way we wanted. Most of them are KCl, not CaCl2. A better option are
dehumidifiers like DryZAir or DampRid (available at most hardware stores
for <$5) - these are pure CaCl2 pellets and they work great.
2) You can precipitate proteins from egg whites by sprinkling them with
salt, or drizzling isopropyl alcohol over them. The proteins denature
and coagulate as white masses.
Jake Ashcraft
OMSI
-----Original Message-----
From: Informal Science Education Network
[mailto:[log in to unmask]] On Behalf Of Jonah Cohen
Sent: Friday, March 02, 2007 8:48 AM
To: [log in to unmask]
Subject: Re: Kitchen chemistry
ISEN-ASTC-L is a service of the Association of Science-Technology
Centers Incorporated, a worldwide network of science museums and related
institutions.
************************************************************************
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A precipitate reaction with kitchen chemicals? Now that you mention
it...
In a Ziplock sandwich bag put 1 tsp of baking soda, 1 tsp of calcium
chloride (aka road salt), then dump in ~20 ml of 0.02% phenol red
solution. Quickly zip the bag shut + smoosh the chems together a bit.
Phenol red isn't really a kitchen chem., but it's pretty safe plus cheap
(half a liter for less than $10).
The precipitate - easy visible on the sides of the bag - is calcium
carbonate aka chalk.
But wait, there's more! You also get color changes, gas production and
temperature change.
Jonah Cohen
Outreach & Public Programs Manager
The Children's Museum
"If you hear only one song this year, there's something terribly wrong
with you."
-They Might Be Giants
-----Original Message-----
From: Informal Science Education Network
[mailto:[log in to unmask]] On Behalf Of Phillip Keck
Sent: Friday, March 02, 2007 11:32 AM
To: [log in to unmask]
Subject: Kitchen chemistry
ISEN-ASTC-L is a service of the Association of Science-Technology
Centers Incorporated, a worldwide network of science museums and related
institutions.
************************************************************************
*****
Hi all,
Does anyone have any suggestions on any precipitation reactions that can
either be carried out with grocery store chemicals, or with chemicals
that are relatively safe?
Thanks,
Phil
Museum of Science & Industry, Chicago, IL
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