How Soap Gets You Clean

Now that you know how soap is made, let’s take a closer look at how it gets you clean.

Here’s a soap molecule:

Soap-molecule-640x198

Can you figure out why it works? Hop in the high school time machine with me and think back to chemistry. Remember this?

DisneyMickeyMouse_xlarge

It’s a water molecule and it’s polar because it looks like Mickey Mouse. The big oxygen atom hangs on to the electrons more often than the tiny little hydrogen atoms, making the O part of the molecule partially negatively charged and the H parts partially positively charged.

Let’s stay in Chem for a little longer; remember “likes dissolve likes”? As it turns out, this rule is the reason that we can get clean. That big long tail on the soap molecule is definitely not polar. It’s a fat and it just wants to chill with all the other non-polar fats. Luckily, non-polar fats are exactly what the gunk on your skin is made out of! When it finds one, it grabs on for dear life. Actually, all the fatty tails of the soap molecules grab on because they love non-polar stuff, forming a ball called a micelle. This particular micelle (my belle, these are words that go together well) has a non-charged inside and a polar surface made up of the polar heads of the molecules. The outside of micelle latches onto polar Mickey Mouse water and carries the dirt down the drain.

532px-Micelle_scheme-en.svg_

For more reading on saponification, check out what happens in fire extinguishers, oil paintings and corpses.

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