Why is soap important? I’m sure you have the idea ingrained in your head that you need to wash your hands before dinner, before cooking, after using the restroom... but why?
Learn more about the importance of hand-washing in the link below!
Hand-washing Dos and Don'ts
Today, our activities are all about soap! First, we will see what happens when we put bar soap in the microwave. What do you think will happen? Next, we will try making a variety of soaps to see which ingredients do the best job of washing your hands!
YOU WILL NEED:
- A variety of bar soaps. Pick 3-4 different brands of bar soap, but one must be Ivory.
HERE’S WHAT TO DO!
- Unwrap each bar of soap.
- One by one, place each bar of soap in a bowl of water and record what happens.
- Do you any of them float? Do they all sink?
- You should have noticed that the Ivory bar floats. Why is it that Ivory floats while others sink? Make a hypothesis!
- You might have guessed that there was an air pocket in the Ivory soap... cut it open and find out.
- Did you find an air pocket? Nope! What could it be?
Explanation: The truth is, Ivory soap IS filled with air, but only in minuscule amounts. There are no large air pockets, but there are tons of tiny little air bubbles whipped into the soap during production. These little air bubbles are what make Ivory soap float.
Now, let’s see what happens when we put Ivory soap in the microwave!
HERE’S WHAT TO DO!
- Place the Ivory soap on a paper towel in the microwave.
- Set the microwave on HIGH for 2 minutes.
- Observe amazingness! What happened?!
- You should have seen the Ivory soap expand much like a marshmallow! Why do you think this happened? Clue: Think about the air bubbles.
- This effect is actually a demonstration of Charles’ Law. Charles’ Law states that volume of gas will increase as temperature increases. How did you see that demonstrated when you put the Ivory soap in the microwave? Explain how your observations relate to Charles’ Law. Learn more about Charles’ Law HERE.
Here’s video that demonstrates what should have happened:
YOU WILL NEED:
- Bar soap
- Small microwavable bowl
- Muffin tin
- Masking tape
- Additives of your choice--could include milk, honey, oatmeal, sugar, cinnamon, etc.
HERE'S WHAT TO DO!
- First, you need to buy a few bars of fragrance free, dye free soap.
- Next, decide which ingredients you would like to add to your soap. A common combination is milk and honey. You could also try using oatmeal or sugar as an exfoliant. You decide! How might adding these ingredients affect the soap’s hand-washing effectiveness? Write down your hypotheses for each combination you create.
- Next, you will melt the bar soap down to a liquid form. Be careful--it does get very hot when melted! Stop the microwave every 30 seconds and stir until the soap is completely melted.
- Mix in your additives with the melted bar soap. Make sure you save one piece of bar soap to use as a control.
- Pour the bar soap mixture into a muffin tin. Make sure you label the tin with masking tape and a marker so you know which soap is which. For example, you might label the row, “Honey Oatmeal,” “Honey Milk,” or “Cinnamon Sugar” depending on what you mixed with your soap.
- Let the soap dry completely. This will take a few hours.
- Now that your soap is finished, try it out!
- Find a few friends to help you determine which soap is most effective. Use a washable marker to draw a line on your friends’ hands. Have each of them use a different soap for 1 minute. Record observations. Which soap washed the marker off most completely?
- Repeat step 7, except have each friend use a different soap than the one before. Did you get the same results?
- Repeat step 7, except have each friend use a different soap than the last two times. Did you get the same results? Continue until each friend has used each soap, including the original, unchanged bar soap.
- Repeat steps 7-9, except use permanent marker. Did you find the same results?
- Repeat steps 7-9, except use pen. Did you find the same results?
- Create a table or graph to represent which soap was most effective in removing the marker, permanent marker, and pen.
Check out our Clean Hands Challenge for another fun experiment about hand-washing!