Question

Find the percentage by mass of oxygen (O) in N2O3 if it is 36.9% nitrogen (N) by mass. (Round your answer to one decimal place.) %

Answer 1

The mass percentage of each element in a compound is defined by:

$\%m/m\text{ = }\frac{mass\text{ of the element}}{mass\text{ of the compound}}*100$

The addition of all the mass percentages has to be equal to 100%.

Then, if we only have 2 elements and we know the mass percentage of one of them, we can find the other one through a subtraction:

$\%m/m\text{ O = 100-36.9 = 63.1 \%}$

Then, the oxygen mass percentage is equal to 63.1%