Computing Molar Mass
Element Atoms in Formula
(NH4)2SO4 		Atomic Mass
grams per mole 		Mass in Formula
N
H
S
O 		2
8
1
4 		14.01 g/mol
 1.008 g/mol
32.07 g/mol
16.00 g/mol 		 28.02 g/mol
  8.064 g/mol
 32.07 g/mol
 64.00 g/mol
Total Molar Mass 132.154 g/mol
132.15   g/mol rounded
6.02x1023 (NH4)2SO4's gives us 132.15 g/mol. This leads to the correct usage of saying "the molar mass of ammonium sulfate is 132.15 g/mol." Other terms commonly used for molar mass include Gram Formula Weight, and the sloppier Molecular Weight. If you always write down the units of g/mol for this number, you will not be misunderstood.