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Name: David H.
Status: student
Age: 20s
Location: N/A
Country: N/A
Date: 2001 - 2002


Question:
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?


Replies:
The first reaction vinegar (acetic acid) + baking soda (sodium hydrogen carbonate) produces CO2 gas, which is what you expected. I can only speculate what occurred when you added iodized salt (NaCl) since you did not describe what you observed take place. My suspicion is you observed the further evolution of some CO2 because the solubility of CO2 in a salt solution is significantly less than its solubility in the vinegar/baking soda solution.

Vince Calder


Well, it's hard to say for sure what you are seeing because you didn't describe the "reaction" that occurs. I am guessing that when you added salt to the mixture, you saw bubbling, similar to the bubbling you saw when you added baking soda to the vinegar.

Most likely, what happened is that you didn't wait long enough after adding the baking soda to the vinegar. The salt doesn't do anything chemically here. When baking soda is added to vinegar, it releases carbon dioxide gas. This gas does not all immediately bubble away; some of it remains dissolved in the solution and only slowly comes out. When the salt is added, it entrains small bubbles of air with it that gives the dissolved carbon dioxide additional surface to diffuse into. This speeds up the process of coming out of solution.

If you saw something else, describe it and we'll try to see if we can figure out what might have happened.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois



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