Question

What is the percentage by mass of sulfur in $H_2{SO}_4$?

• A. 16%
• B. 33%
• C. 36%
• D. 42%

Answer 1

Answer: (B)

33%

Let's take sulfuric acid for an example.
Molar mass of $H_{2}S{O}_4=(1.008\times 2)+\left(32.066\right)+(15.999\times 4)=98.078$ g/mol.
So we know, if we take 1 mol or 98.078 grams of sulfuric acid, how much of each element we have. For instance, in 1 mol of sulfuric, we have 32.066 grams of sulfur.