# How can I calculate the percent composition of C2H8N?

Jun 4, 2014

To find the percent composition of C₂H₈N, you divide the total mass of each atom by the molecular mass and multiply by 100 %.

% by mass = $\text{mass of component"/"total mass}$ × 100 %

Mass of 2 C atoms = 2 C atoms × $\left(12.01 \text{u")/(1"C atom}\right)$ = 24.02 u.

Mass of 8 H atoms = 8 H atoms × $\left(1.008 \text{u")/(1"H atom}\right)$ = 8.064 u

Mass of 1 N atom = 1 N atom × $\left(14.01 \text{u")/(1"O atom}\right)$ = 14.01 u

Mass of 1 C₂H₈N molecule = (24.02 + 8.064 + 14.01) u = 46.09 u

% of C = $\text{mass of C"/"total mass}$ × 100 % = $\left(24.02 \text{u")/(46.09"u}\right)$ × 100 % = 52.11 %

% of H = $\text{mass of H"/"total mass}$ × 100 % = $\left(8.064 \text{u")/(46.09"u}\right)$ × 100 % = 17.49 %

% of N = $\text{mass of N"/"total mass}$ × 100 % = $\left(14.01 \text{u")/(46.09"u}\right)$ × 100 % = 30.39 %