Raisins are the best. They’re delicious, and the only fruit (are raisins considered a fruit?) that got its own special name for the dried version. (“Craisin” doesn’t count, because that’s just a blatant ripoff.) They’ve also got great singing voices. Their tiny wrinkles also make them perfect for this lil’ experiment.
Today’s Demo Science science demo is all about chemical reactions and, even more specifically, the byproducts of said reactions. Let’s science, shall we?
Bubble Time, Buddy Boy
For this experiment, you’ll need a large glass jar, water, vinegar, baking soda, and some raisins. Fill your jar about a quarter of the way with vinegar, top it up with water, and stir. Then, add about two tablespoons of baking powder and stir again.
Cool out for a hot minute as you wait for the vinegar and baking soda to react and start making bubbles (this combo is also a great start for homemade cleaning solutions). If no bubbles appear, or you don’t get very many, add more vinegar. (And if that doesn’t work, add more baking soda.)
Now, drop in the raisins, one at a time. You don’t have to put a whole lot of ‘em in there; like a dozen or so should be enough. As is to be expected, they’ll sink to the bottom of the jar. But then what happens? And, more importantly, why?
It’s A Gas!
If everything turns out like it should, the raisins will rise back to the surface, sink back down a bit, then rise up again. The chemical reaction of the baking soda and vinegar produces carbon dioxide gas (among other things); or, carbon dioxide gas (among other things) is a byproduct of the chemical reaction betwixt the baking soda and vinegar.
Because this gas is produced under/in water, it takes the form of bubbles. And, because these bubbles are less dense than the water/vinegar solution, they float to the top of the liquid. These bubbles cling to the raisins’ wrinkles and carry them to the surface. As the bubbles reach the surface, they pop and release their gases into the atmosphere. Without their supporting bubbles, the raisins resink, only to be picked up by fresh bubbles making their way up. This cycle will continue until the baking soda-vinegar reaction is exhausted.