Molar Mass

Molar mass = mass of 1 mol of substance.

so how do I know the molar mass of substance??

Find the Ar in periodic table add a g behind.

TADAAH! you get your Molar mass for a particular atom.

Eg.

Molar mass of Cu = 64 g
Molar mass of N = 14 g

sooooooooooooo

If i ask you how many moles are there in 28 g of N?

remember 1 mol = 14 g of N
so

28 g of N = 28/14 = 2 mols

if i ask you how many moles are there in 32 g of Cu?

Ans: 1 mol = 64 g of Cu
32 g = 32/64 = 0.5 mol


FORMULA

number of mols = mass/ molar mass


Note:
molar mass of a molecule = Find the Mr add a gram behind.

Eg.
molar mass of CO2 = 12 + 2 X16 = 44 g