We found this effect quite by accident. One of Jr. scientist A's new favorite things to do is to mix various ingredients together to see what happens - I think we have a budding chemist! We were adding things to red cabbage-dyed water (a pH indicator). As expected, when we added baking soda, the mixture turned blue, and adding vinegar to the same mixture caused it to bubble and then turn red. What caught us by surprise was that we next added salt and the mixture bubbled again. I had never heard of salt causing a chemical reaction resulting in bubbles, so we did some more investigating. Adding more salt turned the mixture from red (acidic) to purple, as would happen when you added a base, making us think that salt was a base (it's actually neutral). We tried combining vinegar and salt in another cup and got a rather unexciting cup of salty vinegar with no bubbles. After some google-ing, we found out that the salt wasn't actually creating bubbles, it was releasing the carbon dioxide bubbles trapped in our mixture after the baking soda and vinegar reaction. We decided to try adding salt to soda and got instant bubbles again. We even were able to create a little soda fountain (nowhere near as big as the mentos and diet coke reaction, but still cool). Jr scientists A and E both got quite a kick out of this accidental experiment, and I think it will become a new regular experiment.
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