Today’s Wonder of the Day was inspired by Malachi from indianapolis, IN. Malachi Wonders, “How does soap make you clean? ” Thanks for WONDERing with us, Malachi!
When the days seem to be getting longer and warmer, we bet you and your friends likely play outdoors more. Riding bikes, playing tag, kicking the ball around are all fun ways to pass the time after school lets out. And who doesn't like a rousing game of tug of war? All that playing outside sure does make you sweat and it makes you pick up a lot of dirt along the way!
Once you head inside to start getting ready for bed, there's one place you probably need to make a beeline for: the bathroom! As the hot water fills the tub and you start to suds up, you might WONDER, exactly how does soap make you clean?
Does soap contain tiny organisms that eat dirt? Perhaps soap contains radioactive particles that kill dirt and grime? Could soap replace dirty skin cells with clean ones?
Actually, none of these theories pans out. Soap doesn't contain tiny dirt-eating organisms. It doesn't replace dirty skin cells with clean ones either. It certainly doesn't contain any radioactive particles that could kill dirt and grime!
What soap does contain, however, does a very effective job of cleaning for several reasons. To make soap, sodium or potassium salts must be derived from fatty acids by combining them with an alkali (like potassium or sodium hydroxide) in a process scientists call saponification.
The resulting soap molecules consist of a hydrocarbon chain that has a sodium or potassium atom at the end. The hydrocarbon end of the chain is hydrophobic, which means it repels water. The sodium or potassium end of the chain is hydrophilic, which means it attracts water.
This unique structure gives soap its cleaning power. When your hands are dirty, it's usually because oils have attracted dirt molecules, causing them to stick to your hands.
When you wash your hands with soap, the hydrophobic ends of the soap molecules attract the oily dirt, forming a drop of oil surrounded by soap molecules with their hydrophilic ends sticking outward. When you rinse your hands, the hydrophilic ends of the soap molecules allow the suspended drops of oil to be washed away!
So the next time you wash your hands, try to picture all the soap molecules grabbing the oily dirt particles and pulling them off your hands to be washed down the drain when you rinse. You'll also be able to explain to friends and family members what's happening when dishwashing soap cleans those greasy plates!