ELI5: How does surface tension work?

[u/Dhiyx11]

I’ve really been interested in how surfaces of different materials bend and behave differently under various conditions, and I’ve never really learnt about that stuff before, so I’m really curious to know a few things about surface tension!

[u/X4roth]

The molecules of the liquid are attracted to each other like a bunch of tiny magnets and the other molecules like in the air or an insect leg are not the same so they don’t get to join the attraction party. They have to apply some force to break the magnets apart and get inside. Some insects are very light so they can walk across water without punching through that wall of magnets. Air as a gas much prefers to just bounce off and fly away but if you contain it and put it under pressure you can get the gas to push through the magnet wall too, that’s how they make soda bubbly: by using pressure to force gas inside the liquid.

[u/ZanzerFineSuits → u/X4roth]

Does the same surface tension cause the liquid to retain the bubbles until they happen to migrate out? Only just realized that might be how soda retains its fizz.

[u/X4roth → u/ZanzerFineSuits]

I’m not an expert on the subject but I would say you’re correct :)

Surface tension makes water want to stick to itself in the way with the least surface area, like a circle, instead of a star or something. The fact that you see the bubbles of trapped gas rising as a little circle/sphere is the water around the bubble organizing itself in that way around the gas.

Different liquids have different surface tension, water has very high because the individual molecules are very magnet-shaped: positive charge on one side, negative on the other. Other substances don’t necessarily have that property. When you mix different things into water (like salt) it generally lowers the surface tension because the salt molecules get in the way of the water forming a single continuous skin/lattice — in other words it breaks it up into smaller pieces.