今天帶大家來了解一下Elephant’s Toothpaste ：大象牙膏實驗。
大象牙膏實驗的原理是由於使用碘化鉀(potassium iodide)或者酵母(Yeast)等物質作為催化劑(catalyst)，加速了雙氧水(hydrogen peroxide)分解速率，分解出大量氧氣，因為分解速率快，，所以產生了大量的泡泡。這個反應速率取決於雙氧水的濃度，我們在視頻中能看到，隨著濃度的增加，反應速度越來越快。同時，除了肉眼可見的”泡沫山”(volcano of foam)，這個反應還產生了熱，所以也叫做放熱反應(Exothermic Reaction)
What to do?
1. Use a funnel to carefully pour 1/2 cup (118 ml) of the hydrogen peroxide liquid into the bottle
2. Add about 10 drops of your favorite food coloring into the bottle.
3. Add about 1 tablespoon (15ml) of liquid dish soap into the bottle and swish the bottle around a bit to mix it.
4. In a separate small cup, combine the warm water and the yeast together and mix for about 30 seconds. It should be about the consistency of melted ice cream – add a bit more warm water if needed.
5. Now the adventure starts! Use the funnel to pour the yeast-water mixture into the bottle and watch the foaminess begin!
How does it work?
Foam is awesome! The foam you made is extra-special because each tiny foam bubble is filled with oxygen.The yeast acted as a catalyst; a catalyst is used to speed up a reaction. It quickly broke apart the oxygen from the hydrogen peroxide. Because it did this very fast, it created lots and lots of bubbles. Did you notice the bottle got warm. Your experiment created a reaction called an Exothermic Reaction – that means it not only created foam, it created heat! The foam produced is just water, soap, and oxygen so you can clean it up
with a sponge and pour any extra liquid left in the bottle down the drain.
This experiment is sometimes called “Elephant’s Toothpaste” because it looks like toothpaste coming out of a tube, but don’t get the foam in your mouth!
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