Moles, and molarity

Ok so yes this is very basic but I am just going to review what a mole is and what molartiy is.

First off 1 mole is a number and it is equal to 6.022*10^23 atoms.

The magic of this number is that the mass of a mole of some particular molecule is equal to its molecular weight, so 1 mole of O2 equals 32g.

Molarity is usually used for a solution, and the units of molarity are usually Moles/liter, (or some mole/volume)

so if there were 1 moles of some molecule in 3 L of water the Molarity would be 1/3 or .333333 moles/L