Baking Soda, and Salt
Name: David H.
Date: 2001 - 2002
When I mix apple vinegar and arm and hammer baking soda I
create a reaction (up to this point i understand what is happening), then
I go on to add family dollar store brand iodized salt this creates
another reaction. What happen to create this reaction? Is it creating
the reaction as if I where to stir it or did it create a completely
As you may already know, the first reaction produces bubbles of carbon
dioxide (CO2) gas. The CO2 is fairly soluble in water. When you add salt
the irregularities and tiny corners on the salt crystals provide nucleation
sites on which CO2 bubbles begin to form. In a sense, the salt is driving
the dissolved CO2 out of solution. When the bubbles finally grow large
enough, they break free and rise through the solution.
The first process (vinegar plus baking soda) is an example of a chemical
change. The second process (adding salt to the solution to drive out CO2) is
an example of a physical change.
You should be able to produce the same effect with almost any finely
granulated material. As an experiment, try a little powdered sugar. Try it
to see if sugar is as effective as salt.
When I mix apple vinegar and arm and hammer baking soda I create a reaction
(up to this point I understand what is happening), then I go on to add
family dollar store brand iodized salt this creates another reaction. What
happen to create this reaction? Is it creating the reaction as if I where
to stir it or did it create a completely separate reaction?
I believe you are correct in the first part of your hypothesis. To my
knowledge you are not witnessing a different chemical reaction but you are
witnessing a physical reaction. When you added the baking soda to the
vinegar you created a large excess of CO2 that is residing in the water.
When you added the salt you gave the CO2 saturated solution many more sites
in which to bubble off.
This is actually a very good question and as a side note: In chemistry labs
chemists that would desire to expedite their chemical reactions, add an
inert material called boiling chips to their flasks in order to increase the
contact area for reactants to react.
Another side note: This is kind of similar to superheating water in a
microwave. If you were to heat water in a VERY SMOOTH glass in a microwave
it is quite possible to achieve temperatures above 212 F even at 1 atm
pressure. The reason for this is that the water has no imperfections in the
glass in order to form a site for a gas pocket to nucleate. I WOULD CAUTION
AGAINST TRYING THIS UNLESS YOU HAVE DONE IT BEFORE YOU COULD BURN YOURSELF.
I hope this has been informative,
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Update: June 2012