Yellowstone in the Kitchen - More Fun With Baking Soda and Vinegar

The Man of the House was away overnight, across the state, at a youth retreat, with our oldest two, leaving me with bored little ones, left out of the action, at home.  It seemed like a good time to mix up a really messy, vinegar and baking soda fueled bit of fun.

Like most homeschoolers, we've already made just about every type volcano themed experiment, safe for children, out there - vinegar and baking soda filled, play dough craters...

...salt, oil and water lava lamps...

...hot and cold water density eruptions...

...and what seems like countless other variations on the theme.  The only one I can think of, that we haven't attempted has been the melted wax under sand, in a mason jar submerged in a pot of boiling water.  It does sound temptingly interesting, but risky.  Besides which, we used up the last of our sand, planting our peanuts.

I wondered if we we could't come up with something similar, but less dangerous, using the "ingredients" we had on hand.  The children were still very gung-ho to mix something with vinegar and baking soda.  So, with that in mind, we started out with a jumbo test tube (or recycled Gak container, as it happens)...

...and added a small amount of vinegar mixed with red food coloring (to make it easier to see).

Then, we dropped in a half teaspoon of baking soda, followed quickly by a layer of salt.

The idea was to cover the acid and base reaction, so gas bubbles would build, and burst through the surface of the salt. The problem was, we ended up "smothering" the reaction, rather than just covering, as it rose quickly, and required too much salt to cover the bubbles.

We tried again, starting out with baking soda dissolved in water, in the bottom of a glass mixing bowl.

This time we covered the liquid with corn starch, thinking towards a non-Newtonian topping...

...and then added vinegar underneath the corn starch, inserting it with a straw.

That gave us a nice bubbling reaction, bursting out of the hole made by the straw, and then continuing to bubble...

...and burp for a while.

But, we couldn't really see what was going on underneath. So, we tried again, this time in a drinking glass, and mixing the baking soda, food coloring, and vinegar together, then quickly covering it with cornstarch.

The cornstarch filled the center of the glass, pushing the fizzing baking soda/vinegar mixture to the sides, where it etched interesting tunnels, and pumice rock-like designs into the cornstarch as it mixed with the gas filled liquid, and then hardened.  That was pretty neat.

However, since the reaction was not strong enough to push through the hardened layer of cornstarch, to the surface, we gave it one last try, this time adding baking soda, food coloring and vinegar to the bottom of a clear plastic canister, then covering it with flour, rather than cornstarch.  We met with success when we dug a hole, with a spoon, to the bottom of that same flour glop filled container, and poured in a little more baking soda and vinegar (this time without food coloring, because we'd really given up, and were just messing around), then collapsing the "tunnel" with the spoon.

At first the vinegar and baking soda reaction pushed right up to the surface...





But then, the reaction on the surface calmed down, and seemed to stop.

We could see through the sides of the jar, that under the surface, bubbles were continuing to form and fizz.

And, after while of watching the bubbles through the plastic...



...things started happening again on the surface, but in a slow, blopping kind of way, that reminded me of the mud or "paint" pots at Yellowstone.

And, even if it didn't look exactly like Yellowstone in the kitchen, with all the flour, cornstarch, baking soda, food coloring and vinegar fumes wafting through the air - it was certainly starting to smell right.

It's great to be a homeschooler.

Linked with Science Sunday at Adventures in Mommydom.