Macademics: Why Soap Works

Hey Everyone! I hope you all are staying healthy and inside. Since it's the first Thursday of the month, we have another installment of Macademics for you. I thought it was important to write a follow up post to last month's installment (where I talked about bacteria vs. viruses) and give you all the 411 on why washing your hands with regular bar soap, and NOT anti-bacterial soaps, is so important. As the resident chemist of #MacScientist I want to make sure you all understand, at the molecular level, what's actually going on so you can educate your peers when they're freaking out about the low alcohol content-hand sanitizer (which is good for bacteria) being sold out and how they don't need to use regular soap. So here we go:


What is soap?


Soap molecules have a hybrid structure, the head is hydrophilic (loves water) and the tail is hydrophobic (hates water). While the head of soap molecules bond to water, the tail likes bonding to oils and fats. When you mix soap and water, the soap molecules assemble themselves into micelles (think bubbles), with the heads (parts that like water) pointing outward to interact with the water and the tails (parts that hate water) congregating together to get as far away from the water as possible.


What is the coronavirus?


So this virus is composed of these key pieces: RNA (what carries the genetic information of the virus), proteins, and lipids. For coronaviruses, the outside layer consists of oily lipids and this is how they interact with your skin. In chemistry we say, "Like dissolves like," or "Like likes like" which in this case means that the proteins and lipids of the virus are attracted to the ones on your skin, thus leading to infections if you touch your face a lot and it enters the body. The goal then is to find a way to break the attraction of the outer layer of the virus to your skin.


Following me so far?


How does this go together?


So we know that soaps have a hybrid structure that consists of a head that likes water and a tail that likes fats. We also know that the outer layer of a virus is made of oily lipids. Want to know what else are lipids? Fats! This means that the tails of soaps would also be attracted to the outer layer of the virus. What happens is if you have virus particles on your hands and you wash them with bar soap, the hydrophobic tails of the soap molecules can disrupt their lipid layers so they can no longer bond to your skin, causing them to come right off. Not only can soap break the interactions between the virus and your skin, it can also break the interactions of the lipids on the virus itself so it falls apart. In other words, as the soap molecules form micelles, they can trap particles that are attracted to the hydrophobic tails (dirt, oils, fats, etc.) inside and it all gets washed away in the water. Pretty strong stuff I'd say.



Now you know why everyone is pushing you to wash your hands with regular bar soap. It does some pretty heavy duty stuff with COVID- 19 so be sure you're stocked up on that and wash your hands immediately after coming home from work, the store, or getting packages and deliveries. You can never be too careful.


Stay safe and soapy!

-The Chemist









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