Bleeding Soap

Day 94;

It's the day back from spring break and we're already at Dr. K-pHun's Colorful Demo #3! Here's what happened:

Mr. Bender got soap.
(In period 7, it was soap from Best Western)
He rubbed his hands on it, but nothing happened ):
But then--!
Mr. Bender put water on the soap,
and it began to BLEED!!

So what happened?

There was obviously something going on when the water hit the soap. We know it wasn't just soap and water, because Borah and I did have a bit of a clue: Borah saw Mr. Bender put some clear liquid on his hands before the demo. So whatever it was he put on his hands made the water turn red!

So what was it?

Well we know that water is neutral. Well it's supposed to be, though the tap water in our classroom is less than pure. And we know that soap is basic (we learned that fairly early in the year). Water + soap = basic solution. SO, whatever that liquid was, turned red in bases.

Possible solution: Phenolphthalein?

Phenolphthalein is an indicator, so would change colors in a basic solution. Check!
Phenolphthalein turns red in bases. Check!
Phenolphthalein would be colorless on Mr. Bender's hands. Check!

Mystery solved!