How do you Calculate the mass percent composition of nitrogen oxide?

There is a formula to calculate the mass percent composition (which can be found in your reference table T for chemistry students)

mass of element

----------------------- X 100

gram-formula mass

First of all you need to find the gram formula mass:

2 N atoms= 2(14.0 amu) = 28.0 amu

6 O atoms= 6(16.0 amu)= 96.0 amu

then add together

124 amu

Then plug in with the formula:

(2X 14)

----------- X 100% = 22.58% = % Nitrogen

124 amu

To check to make sure the answer is correct the percentages of the individual elements must addd up to 100%. So you would then need to find the % oxygen. which is 77.41%. So in this case 77.41%

+ 22.58%

is 99.99% which can be rounded to 100% so in this case the answer is correct.