Cranberry Science Follow Up - Where Did All The Color Go?

After our cranberry indicator puzzle yesterday afternoon, I grabbed my oldest (age 14), my laptop, and a number of additional chemicals to test, to see if we could get to the bottom of where all the color had gone from our last experiment.

First off, we had to recreate the experiment a number of times, mixing baking soda into our cranberry indicator solution...


...turning it purple...


...then adding lemon juice, to make it clear...


...and finally adding a good deal more baking soda, to turn it back to purple, which you can see going on in the background of the picture below. What's really important though, is the two cups in the front of the picture, with arrows pointing to them.

The one on the left contains salt water (using plain old table salt - NaCl) mixed with the indicator (and you can see it's made the cranberry juice turn clear), and the one on the right has another salt water solution, this time containing sodium citrate (or really trisodium citrate, I think) - which just happens to be what you get (along with some water and carbon dioxide) when you combine baking soda, or sodium bicarbonate (NaHCO3) with the citric acid (C6H8O7) of lemon juice.

Kudos to SaraElisabeth for being on the right track in the comments, yesterday!

Oh, and it has been a long, LONG time (Ronald Reagan was president), since my high school chemistry days, so don't quote me on any of the above. The point is, the answers are out there if you really want to find them - and that is what unschooling is all about.


Once we realized that salt water essentially made our cranberry juice disappear, we had to give it a try as an invisible ink, writing out a few messages on paper, with fingertips dipped in salt water. We allowed them to dry, and then attempted to make the messages appear with lemon juice soaked cotton balls.


Our results were a little lackluster (slightly better than the evening photo below shows, but still not the best we've ever done with invisible ink). There are probably better invisible ink experiments out there.


However we did have quite a bit of fun with some imaginative play. "Oh no! I've spilled by cranberry juice on the white carpet."


"But, never fear, it's baking soda and lemon juice to the rescue."


"A smidge of baking soda..."


"...a few drops of lemon juice..."


"...for fizzing, stain removing magic."


"Rinse away the residue, and the stain is gone!"


Unless of course, you have a sister (like Candace from Phineas and Ferb), who has a bottle of lemon juice herself - then, your busted, as she makes the stain reappear.



It's great to be a homeschooler.