Question

How can I calculate the percent composition of C4H4O?

Answer 1

To find the percent composition of C₄H₄O, 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 4 C atoms = 4 C atoms × `(12.01"u")/(1"C atom")` = 48.04 u.

Mass of 4 H atoms = 4 H atoms × `(1.008"u")/(1"H atom")` = 4.032 u

Mass of 1 O atom = 1 O atom × `(16.00"u")/(1"O atom")` = 16.00 u

Mass of 1 C₄H₄O molecule = (48.04 + 4.032 + 16.00) u = 68.07 u

% of C = `"mass of C"/"total mass"` × 100 % = `(48.04"u")/(68.07"u")` × 100 % = 70.57 %

% of H = `"mass of H"/"total mass"` × 100 % = `(4.032"u")/(68.07"u")` × 100 % = 5.923 %

% of O = `"mass of O"/"total mass"` × 100 % = `(16.00"u")/(68.07"u")` × 100 % = 23.50 %