Mole is used to measure mass (I think) and molecules. Also a mole is a "starter" (talk about it liek it's Pokemans) unit, along with seconds, meter, kilogram and amp. Other units of measurements derive from these units, for example, grams and centimetres as centimetres (as you know) are used to measure one unit out of one-hundred. So basically these were derived from their original units to make it easier to measure things because (as Keenan said) one mole is about 18 ml of water, and greater than the total number of grains of sand in the world. So it would be almost impossible to calculate mass on that scale. And it's actually Physics not Chemistry.