Thursday, January 2, 2014

Red Cabbage pH Indicator

The kids are fascinated with chemistry! We're still studying acids and bases, doing a lot of playing and demonstrating while reinforcing the concepts (mental note: I NEED to figure out a good, buildable molecular modeling system ASAP), and so the other week Syd and I made red cabbage pH indicator for us to play with:

(Don't you just love our manky kitchen? The top of the microwave is the official place to cram all the dish towels, and yes, our countertops are made out of genuine plywood, but not the kind that leaches chemicals into your food. I think...)

Red cabbage pH indicator is the BEST thing to make! It's super easy and super fun to play with, and the vividness of the reactions makes them really satisfying. And unlike a lot of what we've been doing for chemistry so far, we don't know what most of these reactions will be in advance, which makes this an actual experiment, not a demonstration--yay!

So grab a liquid from wherever, pour a little bit into a test tube, add a little red cabbage pH indicator, agitate, and observe. Did the liquid turn a shade of beautiful pink?

You've got an acid!

Did your liquid turn gorgeous blue?

It's a base!

Can you actually not figure out what it's doing?

Yeah, that happens, too.

See, who ever said that organic chem was nothing but a weed-out class, anyway?

The kids had a marvelous time collecting various reactions-- 

--so much so that they *almost* didn't mind me making them write down all their observations, scientific-like.

And when they were thoroughly done playing, we still had over a pint of red cabbage pH indicator left to put in the refrigerator for later play:

Although how we could forget about that when we were dissecting batteries yesterday, I do not know. Bummer!

There are still a few activities that we could do for further study of acids and bases:
We almost need to do a unit on atoms and molecules, though, before really proceeding much further, since I know the kiddos aren't understanding my explanations of hydrogen and hydroxide and why they want to be given up and re-combined, and Will's been getting very interested in the periodic table of elements lately, so it's possible that we'll switch instead from straight chemistry to a unit study on the elements that encompasses chemistry and other scientific and historical concepts...

Isn't science so exciting? 

P.S. If you've know of a good, buildable molecular modeling system, hit me up with it! I *want* the Zometool Molecular Mania Science Kit, since I already have a billion other Zometools, but I'm wondering if I could just spray paint the spheres in the kit that I already have to be the correct colors and score a bootleg copy of the instructions, instead. Or I could use gumdrops and toothpicks, but I'd end up eating the gumdrops. Hmmm...

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