I was looking on the [Wikipedia page](https://en.m.wikipedia.org/wiki/SI_base_unit) for all of the base SI units, and was surprised to see that mole was considered a base unit.
Why is this even a unit? Shouldn’t it be a unit-less quantity? A mole isn’t length, or time, or mass, it’s just a number. Why does it need a unit if it just represents “6×10²³ of something”?
You don’t need units to say “I have 15 pencils,” so why is the mole necessary? It seems like a mole is just a scalar.
In: 10
Moles are used for finding out a rough but fairly accurate number of molecules or atoms you have. This can be very useful in chemistry because it allows you to balance reactions etc.
So how does it work? We know that any atom or molecule weighs roughly the weigh of a neutron times how many neutron/protons it has, and if we need more precise methods there’s options for that. That’s called the molar mass. We know that if we have 20 grams of a compound each weighing 20 molar mass, then there will be 1 mole of these molecules. That’s because 1 mole is equal to the amount of atoms with x molar mass in x gram.
Therefore any time we know what something is made of + how much it weighs, we can calculate how many molecules we have.
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