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Hand washing: How does soap work and is hand sanitiser better?

Donna Coutts, March 17, 2020 6:45PM Kids News

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Abigail with soapy hands during a thorough hand washing session to clean her hands of dirt and germs. Picture: Glenn Campbell media_cameraAbigail with soapy hands during a thorough hand washing session to clean her hands of dirt and germs. Picture: Glenn Campbell

explainers

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As people around the world work to slow the spread of the virus called COVID-19, everyone is telling us to wash our hands with soap.

If you’re following this advice from the government, doctors, scientists, teachers and parents, you’ve probably never washed your hands as often or as thoroughly in your life.

But is soap really necessary? Does soap work? How does it work? Can’t you just use water? Is hand sanitiser better?

DOES WATER CLEAN YOUR HANDS?
Not well enough.

Germs such as bacteria and viruses stick to the natural oil (a type of fat) on your skin. Water without soap isn’t very successful at getting the germs off your skin because water and oil don’t mix.

WHAT IS SOAP?
Soap is made with some kind of fat or oil, water and some kind of alkaline* substance, such as a type of salt. It sometimes also has small quantities of other things in it, such as perfumes or colours.

Ancient humans were making soap thousands of years ago using animal fat and wood ash, which is the alkaline ingredient. When the fat and the alkaline ingredient are mixed together with the help of some water, there is a chemical reaction, called saponification. Soap is the result!

HOW DOES SOAP WORK?
The molecules* of soap, incredibly, have one end that loves water and one end that loves oil.

If you wash your hands with soap, the soap molecules act as a link between the water you’re washing with and the oil on your skin. A molecule of water joins to one end of the soap molecule and a molecule of oil joins to the other end.

When you rinse your hands, the whole lot washes off, lifting the oil off your skin and taking the germs with it.

Also, scientists have looked at particles of COVID-19 virus under a microscope and know it is what is called an “envelope virus”, which means each particle has a coating of fat molecules around it. When you wash your hands with soap, the coating falls apart, destroying the virus particle.

Parents clueless about preventing colds in kids media_cameraSylvie and brother Curtis washing their hands with soap. Picture: Tim Carrafa

DO I NEED TO DRY MY HANDS?
Germs love damp environments, so drying your hands is important. Disposable paper towel or a hand dryer is best if you are in a public bathroom.

TV dog Bluey is helping kids wash their hands properly to the tune of Bluey's song Poor Little Bug On The Wall. If sung twice, the song lasts for 20 seconds, the recommended time to ensure your hands are ‘bug-free’. media_cameraTV dog Bluey is helping kids wash their hands properly to the tune of Bluey’s song Poor Little Bug On The Wall. If sung twice, the song lasts for 20 seconds, the recommended time to ensure your hands are ‘bug-free’.

IS HAND SANITISER BETTER?
Many hand sanitisers are made with a type of chemical called ethanol, a form of alcohol. To kill germs such as viruses, the hand sanitiser has to have a minimum of around 60 per cent alcohol in it. The alcohol can kill virus particles much like soap does, but you have to soak every part of your hands thoroughly with the sanitiser. For this reason, a squirt of sanitiser gel or a wipe may not be thorough enough.

If it isn’t possible to wash your hands with soap and water, hand sanitiser is useful.

For more information on hand washing visit healthdirect.gov.au/hand-washing

media_cameraVolunteers stand ready to provide soap and water for participants to wash their hands against COVID-19 at a women’s 5km fun run in the capital Addis Ababa, Ethiopia on March 15, 2020. Picture: AP

GLOSSARY

  • alkaline: a chemistry term that means opposite to acidic
  • molecules: smallest pieces of a substance, which need to be seen under a microscope

EXTRA READING

Too many dirty hands to be healthy

Ban on crowds to help limit spread of COVID-19

We are losing the war on superbugs

QUICK QUIZ

  1. Why isn’t just water good enough for hand washing?
  2. What did ancient humans use to make soap?
  3. What happens when you rinse soap off your hands with water?
  4. Describe the two ends of a soap molecule?
  5. What is one ingredient of hand sanitiser?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. Washing Jingle
Work with a partner and think of a little jingle and jig to teach others about the importance of washing hands with soap. Use some of the information contained in the Kids News article and the experts’ advice that you should wash for 20 seconds and then dry hands thoroughly.

The little dance or jig you make up needs to take into account the hands are busy under the sink so you have to use other body parts!

Perform your jingle and jig to the class.

Time: allow 25 minutes to complete this activity
Curriculum Links: English, Dance, Personal and social, Critical and creative thinking

2. Extension
What could you change at your school or home to ensure less germs in public areas and more hand washing to occur? Write a list detailing at least 5 points.

Time: allow 5 minutes to complete this activity
Curriculum Links: English, Critical and creative thinking

VCOP ACTIVITY
Experiment Time
Get a bowl of water and shake lots of pepper or dry spices into it. You want to give the surface of the water a good covering.

In a small bowl, squirt some dishwashing liquid or liquid soap into it.

In another small bowl, squirt a small amount of hand sanitiser into it.

Now it’s time for the experiment.

Dip your pointer finger into the peppery water. Does it come out dirty?

Using another finger, dip it into the hand sanitiser before dipping into the peppery water. Does it come out dirty? As dirty as the pointer finger did?

Using yet another finger, dip it into the dishwashing liquid or liquid soap, then into the peppery water. Did it come out dirty? How does it compare to the other 2 fingers? Did anything else happen?

After the experiment, write up a report on your observations and what we can do to practice best hygiene measures.

HAVE YOUR SAY: How have you changed your hand washing recently?
No one-word answers. Use full sentences to explain your thinking. No comments will be published until approved by editors.

Extra Reading in explainers