Color Changing Liquids part 2

We recently tried an experiment from Steve Spangler Science, one of my favorite sites. You can find full instructions for the experiment….here, though we made a few modifications. Here’s our set up and what was supposed to happen:

The blue and green liquids (test tubes on the right in each stand) were mixed using cold water. The red and yellow liquids (test tubes on the left) were mixed using hot water. We put the blue (cold) water on top of the red (hot) water. We put the yellow (hot) water on top of the green (cold) water. We expected the heat to rise and cold to sink in each situation. So, we expected the cold blue to sink into the hot red and create purple. We expected the hot yellow to be perfectly content on top of the cold green, therefore not mixing at all. This is indeed what the beautiful video on Spangler’s site showed.

However, we learned a thing or two about how precise one has to be with science experiments. Here was our result:

Whoops! This wasn’t what was supposed to happen. The yellow-green at left wasn’t supposed to mix together. However, I had used an old recipe card to separate the two test tubes, before I placed them one on top of each other. Pulling out the recipe card wasn’t easy, and I think I ended up lifting up the top test tube, introducing some air and force that caused the two liquids to mix. Spangler had opted for a waxy playing card, which I’m sure slipped more easily. So, we talked about how careful scientists need to be with their experiments to produce accurate results.

Seriously, if you try this at home, follow Steve Spangler’s lead and use something slippery (a playing card) to separate the two liquids. It will pull out from between the test tubes much more easily. Oh, and this is very messy, so we recommend putting a cookie sheet underneath your workspace. We always have fun with these experiments even when we aren’t successful!

Homeschool, Science/Math, Toys

Chemistry Experiment 2: Color Changing Liquids

Our second mind-blowing science experiment was dubbed “Color Changing Liquids,” an experiment you can easily do at home without special equipment. Our science kit included red cabbage juice powder, which we added to two separate cups of water to create a purplish-colored indicator (a substance that changes color when mixed with an acid or base). To make your own indicator, simply shred some red cabbage and soak it in water overnight. Strain it the next morning, and you are ready to test!

To our first cup, we added citric acid (you could use vinegar), which turned the liquid red. To the second liquid, we added baking soda, which turned the liquid blue, indicating a base. Then, we mixed the two liquids together. The acid and base neutralized each other, creating a purple liquid and released carbon dioxide just like in the “dancing powders” experiment.

Steve Spangler Science has some variations on this experiment. These include ideas for other acids and bases to test and  how to create your own pH  test strips from red cabbage juice. Enjoy!