And why are they starting from the metal bottom?
And why the bubbles disappear in the middle???
https://streamable.com/notzi
In: Chemistry
As water heats up, it begins by getting rid of dissolved gas. This includes nitrogen and oxygen and carbon dioxide and argon (air). Normally water can hold onto these gases but as it heats it is no longer able to.
As it heats more, the water itself *becomes* a gas (steam) and forms even *more* bubbles.
In both cases, the reason for bubbles forming on the metal bottom is twofold:
1. The bubbles usually form where the water is hottest, which *tends* to be right at the metal which heats it
2. In chemistry, there is something known as a nucleation site. This is a place which contains some small irregularity, such as a dust speck or a microscopic scratch on a surface, and some interactions or reactions happen much more quickly at these sites. The liquid water contains very few nucleation sites, as it is more or less all the same, but the metal siding is covered in microscopic scratches and such and is absolutely *littered* with nucleation sites.
The bubbles are water.
Specifically, the bubbles are water that has changed from the liquid state to the gas state, steam. The reason bubbles form on the bottom of a pot is because that’s where the heat is greatest. When bubbles get to the top of the water, they evaporate.
The bubbles are steam, the water near the heating element is heating up faster than the rest of the water so it vaporizes and forms bubbles of steam which then rise to the surface.
Latest Answers