[ELI5] How does a glass of water standing for a while create small bubbles on edge of the glass?
In: Chemistry
This is a phenomenon called Nucleation. When you have something dissolved in water, and you introduce the water to a rough surface, the dissolved things come out of the water.
Air is always mixed with water in a small amount, because air is all around us.
Normally, air would leave the water through the top of the glass.
There are tiny nicks or rough spots you can’t see in the glass, where the air wants to come out, and it makes a tiny bubble. Then the bubble covers the nick, and no more air comes out.
This is best demonstrated with making sugar candy. You take hot water, dissolve a ton of sugar in it, then let it cool. Now the water has more sugar than it should be able to dissolve. When you put a string into the water, the sugar nucleates onto the string. Voila, you now have sugar crystal rock candy.
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