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Moles confuse me- why are they used?
Think of moles as a "chemist's dozen". Just as 12 eggs is a dozen eggs, 6.02 × 1023 eggs is a mole of eggs.
6.02 × 1023 molecules of oxygen is a mole of oxygen.
The number of grams in a mole is different from substance to substance. If you're like most students, it's this
that's confusing you.
Picture it this way: a dozen elephants have a different weight than a dozen rabbits- but in each case, you have a dozen animals.
Similarly, a mole of oxygen gas has a different weight than a mole of water- but in each case, you have 6.02×1023
Why use moles?
You often want to know how many molecules you have in a sample of a substance. Counting the molecules
individually would be completely impractical. Even if you had a way to see the individual molecules, there are just too many, even in a tiny sample.
Moles were defined to solve the problem of counting large numbers of molecules.
With moles, you count the number of molecules in the sample by weighing it.
Learn to convert between moles and molecules, and moles and grams.
Author: Fred Senese firstname.lastname@example.org