Question

How can I calculate the percent composition of C2H8N?

Answer 1

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 = `"mass of component"/"total mass"` × 100 %

Mass of 2 C atoms = 2 C atoms × `(12.01"u")/(1"C atom")` = 24.02 u.

Mass of 8 H atoms = 8 H atoms × `(1.008"u")/(1"H atom")` = 8.064 u

Mass of 1 N atom = 1 N atom × `(14.01"u")/(1"O atom")` = 14.01 u

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

% of C = `"mass of C"/"total mass"` × 100 % = `(24.02"u")/(46.09"u")` × 100 % = 52.11 %

% of H = `"mass of H"/"total mass"` × 100 % = `(8.064"u")/(46.09"u")` × 100 % = 17.49 %

% of N = `"mass of N"/"total mass"` × 100 % = `(14.01"u")/(46.09"u")` × 100 % = 30.39 %