When you’re boiling a pot of water, right before the water starts to boil if you watch carefully at the bottom of the pot there will be tiny bubbles that form and disappear. Why do they just disappear instead of floating up to the top once they’re already formed??
In: Physics
Good question!
The bubbles you are at the bottom are actually not the same as the bubbles that you are thinking of!
The one that you’re thinking of are air bubbles, when you put a straw into the bottom water and blow air into it, the air gets pushed into the water and rises to the top.
When you boil water, some of the water at the bottom of the kettle gets so hot they turn into steam! Steam looks exactly the same as air, but with one exception – they like to give out heat and when they do, they shrink and turn back into water.
So just as the water starts to boil, these tiny stream bubbles form, but since it is surrounded by water that’s not yet at boiling temperature, they almost immediately shrink and turn back into water.
This process repeats until all water in the kettle gets to 100 degrees C, when steam can’t shrink anymore, and start rising to the top!
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