# What is the percentage by mass of SO_3?

Oct 7, 2016

$\text{% sulfur by mass}$ $=$ (32.06*g*mol^-1)/(80.066*g*mol^-1)xx100% $=$ ??
$\text{% sulfur by mass}$ $=$ (32.06*g*mol^-1)/(80.066*g*mol^-1)xx100% $=$ ??
$\text{% oxygen by mass}$ $=$ (3xx16.00*g*mol^-1)/(80.066*g*mol^-1)xx100% $=$ ??
The sum of the individual percentages =100%; why?