Sorry, my title isn’t too clear… I’m looking for something I can do at home with my 4-year-old using regular stuff from the kitchen or whatever to cause a bubbling reaction that can be stopped by the addition of something else. Vinegar and baking soda causes the kind of reaction I’d like, but fizzes itself out too quickly - I want to be able to watch for at least a couple of seconds, and then throw something else in to stop it immediately. Is there such a thing? Any ideas? Thanks!
I’m not aware of anything commonly fond in the household that will give you those results. What lesson are you teaching? A cool bubble experiment is to drop raisins into Sprite. Bubbles will slowly form on the raisins which will float. The bubbles pop at the surface and the raisin sinks and the cycle repeats.
Maybe a simple water electrolysis experiment with some batteries, wire, and water? The bubbles will be tiny, but you’ll be able to stop them by cutting the current to the cell. Youtube should show some good examples. What’s actually going on in the cell is probably a bit much for a 4 yo to grasp, however. Then again, it’s only a bit more complicated than a simple acid/base reaction.
Some dry ice in a glass of warm water will give you lots of bubbles and smoke to boot, but I can’t think of any way to kill the bubbles after a few seconds (other than using tiny pieces of dry ice). Add some soap and you’ve got a foam party!