At-Home STEM Activities: Pepper and Soap Experiment
In this easy, hassle free, experiment, you will use pepper floating on water to demonstrate how soap affects the surface of water. This is a quick experiment and requires few materials, but it surprised me how reactive the pepper is to the soap on the surface of the water, you will want to try it out a few times!
Amidst the coronavirus chaos, everyone seems to be grabbing the hand sanitizer and washing their hands more often than just after using the bathroom. This experiment will demonstrates simply how soap and water removes germs from your hands.
A virus, such as coronaviruses and the flu, is encoded by RNA, or a coat of fat and protein, so when the side of the soap molecule that is attracted to fat and protein inserts itself into the virus’s shell, the chemical bonds holding the virus together are broken apart. The broken virus is not soluble in water, therefore it disintegrates and is washed down the drain.
The novel Covid-19 virus. All coronaviruses are covered with pointy spires of protein, giving them the appearance of having a crown or "corona", hence the name. Coronaviruses use these spikes to latch onto and pierce our healthy cells. Image credit: Center for Disease Control
Pepper and Soap Experiment
Supplies:
Small bowl
Water
Pepper
Dish soap
Toothpick
1. Fill your small bowl with water
2. Cover the surface of the water with a layer of pepper. The pepper flakes should float, not sink, upon the surface of the water.
3. Squeeze a tiny bubble of dish soap onto a clean counter. Touch the tip of your toothpick into the dish soap. You only need a little bit. Get ready to touch your soapy toothpick to the water. What do you think will happen when you do this? Let’s find out! Try to touch your toothpick to the water and see what happens. Once you have done your own, check out the video below!
What were the results?
Most of the pepper flakes should have quickly darted to the sides of the bowl. It may have looked like the soap was chasing the pepper flakes away.
The first question to ask is why the pepper flakes float. Why don’t they sink or dissolve in the water? Well, pepper is hydrophobic, meaning that water is not attracted to it. Because of that, the pepper can't dissolve in the water. But why do the flakes float on top of the water? Water molecules like to stick together. They line up in a certain way that gives the top of the water surface tension. Because pepper flakes are so light, and hydrophobic, the surface tension keeps them floating on top.
The next question to think about is why the pepper shoots to the sides when soap touches the water. Soap is able to break down the surface tension of water—that is why soap is such a good cleaner. As the soap moves into the water, and the surface tension changes, the pepper no longer floats on top. But the water molecules still want to keep the surface tension going, so they pull back away from the soap, and carry the pepper along with them.
This experiment used information found on Education.com
