Ask a Chemist: How does handwashing kill coronavirus?

The physical action of handwashing plus the properties of soap is a one-two punch for the virus.

Ask a Chemist: How does handwashing kill coronavirus? | Kate the Chemist ...

KATE THE CHEMIST: One thing that I found that was super interesting is that this virus actually has a really weak membrane on the outside. And so since the membrane is actually kind of weak when we wash our hands it's not really the soap that's killing the virus, it's that action. It's the movement that you're doing with your hands. So when you scrub really hard you are actually ripping apart that membrane since it's so weak. And so it's that 20 seconds of scrubbing, of using your fingernails and using a scrub brush to actually clean and rip that virus apart so that your hands therefore can be clean when you do a final rinse and that wash rinses the virus off. The cool part about our soap is that it has two different sides. It's hydrophilic and it's hydrophobic. So the hydrophobic part is the part that actually binds to that virus so it hands onto kind of like a middle school crush like you grab onto someone and hang to them really tight and that's what the hydrophobic side does. It grabs that virus and hangs on.
The hydrophilic side is the side that actually likes water. So when the water turns on, the hydrophilic side grabs onto the water molecules and the hydrophobic side grabs onto the virus and so each one has a job. One hangs onto the water, one hands onto the virus and then that entire molecule section is going to drop down and it flushes off your hand down the water stream into the sink. So the scrubbing motion breaks the virus apart and then the soap itself bonds to the water and the virus to remove it completely from your hands and make sure you're completely safe.

  • A common recommendation from experts to help protect against coronavirus is to wash your hands often, but why? It turns out that each time you do it is an effective two-pronged attack.
  • As Kate the Chemist explains, the virus has a weak outer membrane. By using the proper handwashing technique, you're actually breaking through that membrane and ripping the virus apart.
  • Soap is an important part of the equation because of its two sides: the hydrophobic side (which grabs onto the virus), and the hydrophilic side (which grabs onto the water). Washing your hands with soap for at least 20 seconds allows the virus to be rinsed away.

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