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This Doppler 9&10 STEM experiment comes to you straight from my TikTok for your page. If you or your kids have a TikTok, you might have seen this little trick done in the past week. It’s fun to watch but even weirder to try it for yourself!
Essentially, all you need is,
- Cocoa Powder
- A Spoon
- A Butter Knife
- A Cup of Water of Milk (Enough to Submerge your spoon in)
Now its game time,
- Take your spoon and get a heaping spoonful of cocoa powder. It might be best to use the cheapest cocoa powder you can find, wouldn’t want to waste the good stuff!
- Dip your spoon full of cocoa powder in your cup or bowl full of water or milk. As you dip the spoon in, you will notice that the powder doesn’t immediately mix with the water. In fact, the powder will stay on the spoon even if you tip the spoon down.
- Take the spoon out of the liquid. Now you will notice the powder looks wet.
- Take your butter Knife and tap the powder. The wet layer will “pop” and reveal the dry powder underneath!
How cool is that!
Now for a little explanation!
There are a few things happening here. One, cocoa powder is “hydrophobic”.
Normal cocoa powder will contain about 10% to 12 % fat, and fat molecules will naturally push water away. this is the same reason cooking oil and water don’t mix.
Next, the other main part of cocoa powder is starch. Think of flour (another example of starch), when you pour a liquid into the flour, the first areas the water touch will quickly absorb water but as you stir the flour there will be little balls or clumps of flour that look wet but when you break them up, they are dry inside.
The same thing happens here. The starch molecules inside of the powder quickly absorb water but only on the outside of the spoonful of powder. At the same time, hydrophobic fat molecules are blocking water from passing through any holes in the starches. Making a weak barrier that can be “popped” with a little tap, to reveal dry powder inside.
If your kiddos try this experiment, send us photos of you and your experiment and you might get to see it during weather on The Four on Tuesdays!
Make sure you tune in every Tuesday for a New 9&10 STEM. Send us an email at email@example.com or find us on Facebook and at Doppler 9&10 Weather Team if you have a weather question or want something in science explained! It does not have to be weather-related! Anything Science or math-based we’ve got you! You can always get the latest forecast on 9and10news.com/weather as well as interact with us on social media!