Percent composition

Question

what is the percent composition of each element in the compound Na2SO4

Answer 1

Add up the atomic weights of each element:

Na = 22.99 x 2 = 45.98

S = 32.07

O = 16.00 x 4 = 64

TOTAL MASS = 142.05 = 142 (to 3 significant figures)

 

Next, divided mass of each element by the total mass and express as a percentage:

%Na = 45.98/142 (x100%) = 32.4%

%S = 32.07/142 (x100%) = 22.6%

%O = 64/142 (x100%) = 45.0%