Which is the formula mass of #Na_2SO_4#?
Break up the formula compound and see what are the atoms present.
2 atoms of Na, 1 atom of S, and 4 atoms of Oxygen.
Refer to your periodic table and find out the formula mass for each individual atom present.
Na = 23.0
Note: It's multiplied by 2 because there are two atoms of Na.
S = 32.1
O = 16.0
Add the individual formula mass together and therefore it will give you the overall formula mass of
46.0 + 32.1 + 64.0 = 142.1 g/mol is the formula mass of