Question

What is the percentage of sulfur in sulfuric acid (H2SO4)? Why do we have to divide32 from 98u ???

Answer 1

First calculate the relative formula mass of sulfuric acid: 
H = 1 (1 × 2) = 2
S= 32
O= 16 (16 × 4)  = 64

2 + 32 + 64  = 98

98 is the relative mass of sulfuric acid, hence we divide 32, mass of sulfur, with 98 to find mass ratio which we use to get the percentage of the sulfur.

32/98 × 100

= 0.3265 × 100%

= 32.65 %