– Why is water ‘virtually’ incompressible?
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Not a chemist, so someone will be able to poke holes in this explanation. Please do.
Water is made up of three atoms: one oxygen and two hydrogen atoms. They bond because the oxygen atom is able to “steal” the electrons away from the hydrogen atoms. These are called covalent bonds.
What this does is it creates positive and negative sides of the molecule. The hydrogen sides are positive (from their single proton) and the oxygen from the increase in the electrons (2 extra electrons.)
Normally, a molecule like that would have the two hydrogen atoms be as far apart from each other as possible. They’re both positive, they both repel the other, and they don’t WANT to be near each other.
But, in water, the hydrogen atoms are at an angle (104.5 degrees) instead of being opposite to each other (180 degrees). (No, I don’t know why. Water is weird.) This means the entire atom has a strong electromagnetic difference. One side of the atom is positive (between the two positives) and the other side is negative.
Because those differences are across ALL the water molecules, the atoms do not like being near each other. Like, REALLY do not like being near each other. That’s why, even when you make water into a solid (freezing), the water molecules want to stay farther apart than when they’re free to move (liquid). That’s why water is one of the only substances that exists where the solid is less dense than the liquid (ice floats in liquid water).
Yes, you CAN compress water. But, in functional terms f human experience and engineering, that compressibility is negligible.
At 6000 psi, water only compresses 1.8%. There’s not a lot of places where we compress things to 6000 psi, not even in most hydraulic systems. And most other things compress more than that. We don’t use it for hydraulic systems because water under pressure becomes really reactive. It corrodes things.
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