– Why so bubbles form inside a glass of water at room temp if you let it sit long enough?


Why do bubbles form on the inside of a glass of water at room temperature if left alone long enough? Is it essentially underwater evaporation that gets stuck on the side of the glass?

If so, does that mean that tiny microscopic bubbles are forming in the middle of the glass and successfully finding their way to the top all the time?

If both statements are true, this would kinda be the ultimate expression of “a watched pot never boils.” Or maybe I’m just crazy, you tell me.

In: Chemistry

There are two important parts to your question. First, water that you drink from a tap isn’t entirely “water” – it has bits of other things like salts dissolved in it, and that includes air and other gases. Normally, these gases are quite happy to stay stuck inside the water, and very rarely run into each other. This is where the second part comes in.

The inside of a glass isn’t totally smooth – there’s roughness and texture that you can’t see, whether the glass is made of actual glass, plastic, or anything else. The rough parts of the glass make a perfect spot for the gases in the water to attach to. Once a tiny bit of gas is stuck to the wall, it allows other bits of gas to attach to it. After enough time and enough accumulation, this gas becomes a proper bubble.

So your theory is partially right – there are microscopic bubbles forming inside of the glass, they’re just dissolved gas coming out of the water rather than water turning into vapor.

Expanding slightly on u/borkfast’s excellent explanation, what you see in the glass left overnight is basically what you see immediately in a glass of poured champagne: dissolved gases coming out of solution at points of nucleation. There’s just way more dissolved gas in a carbonated beverage than there is in tap water.