Student submitted - Saponification

Today's post was submitted by Aleeyah B, one of my AP chemistry students. As a sub assignment after the AP chemistry exam, I had students submit two posts for this blog. I'll be posting them over the next few weeks.

We use soap every day, I hope, but we rarely stop to think about the chemistry of it. This source tells us that soap is made when a fat or oil made of triglycerides (fat found in blood) reacts with a strong base such as sodium hydroxide. This reaction breaks down the triglyceride molecules and makes something called glycerol (a sugar alcohol) and what we call soap. Every soap molecule has two ends, one hydrophilic and one hydrophobic. The hydrophobic end attracts to the oil and grease (non-polar), while the hydrophilic side attracts to the water (polar). As we wash our hands, the soap is able to grab the oil, but is also able to be washed away by the water.

Something that I thought was funny was that soap doesn’t just murder all the germs on your hands, but actually washes them away. I always thought soap instantly killed any bacteria it touched, and not necessarily washed them away.

You can learn more about saponification at this link.