After today’s post, you might never look at a glass of water the same way again.
The water molecule is made of two hydrogen atoms plus one oxygen atom, arranged in a Mickey Mouse shape, with the chemical formula H20. You already knew that, I’m sure. But you may not be aware of this: water’s chemical formula gives you a hint about water’s true nature.
Hydrogen ions play an important role in acid/base chemistry, so when you see hydrogen listed first in a chemical formula, that typically indicates that you’re looking at the chemical formula of an acid.
- Acid: an acid is a chemical that can give up a proton (a.k.a. a hydrogen ion) to a base.
- Base: a base is a chemical that can accept a proton from an acid.
Water can do both. It’s an acid. It’s also a base.
- Acidic Water: a water molecule (H2O) can give up a proton to a base, transforming itself into a hydroxide ion (HO–).
- Basic Water: a water molecule (H2O) can accept a proton from an acid, transforming into a molecule called hydronium (H3O+).
Now this is where things get really freaky: because water is both an acid and a base, it can actually react with itself.
In fact water is constantly reacting with itself. The result is that even “pure water” is really a mix of water, hydroxide, and hydronium in a proton-swapping party that never ends.
Something to think about the next time you drink a glass of water.
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Today’s post is part of a special series here on Planet Pailly called Molecular Mondays.
On the first Monday of the month, we take a closer look at the atoms and molecules that make up our physical universe, both in reality and in science fiction.