BrainStorms: Science with Scottlin – Hydrophobic Powders

Science With Scottlin

JACKSON, Miss. (WJTV) – Here is another super quick and easy experiment that will have you questioning if this is science or magic.

GRAB YOUR INGREDIENTS: a bowl of milk, glass of water, cocoa powder, cinnamon, a spoon, and a toothpick

STEP 1: Get a spoon full of cocoa powder

STEP 2: Dip the spoon into the bowl of milk.

NOTE: Be sure to keep the powder in the spoon when you do this

STEP 3: Poke the powder with your toothpick

Science behind this experiment: Wait. Let’s rewind. This powder was dry, then wet, now its dry again??

The way the cocoa reacts to the milk shows the hydrophobic characteristics. Hydrophobic meaning it repels water or in this case, milk. Speaking of water, that will work too, if you’d rather use water instead of milk.

NOTE: If we had fat free milk, this wouldn’t work at all. If you tried, the powder would just float to the top when you put the spoon in.

We can call cocoa mildly hydrophobic because it repels the milk, but it attracts air. When you dip the spoon in the milk, an air bubble is formed around the powder and a milk bubble is formed around the air. When you pull the cocoa out, air is trapped between what looks to us as wet, and the actual dry powder. There is surface tension around the cocoa, so when you stick it with the toothpick, it pops, kind of like a balloon.

NOTE: Move to the glass of water

STEP 4: Cover the top of the water with cinnamon

STEP 5: Dip a finger in

Science behind this experiment: Your finger doesn’t come out wet as you may have thought it would. It is still completely dry. This is because cinnamon is hydrophobic too and there’s a layer of air around your finger preventing it from getting wet.

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