Practice 8.5 Percent Composition
1. Calculate the % composition of Li2O.
2. What is the percentage composition of a carbon-oxygen compound, given that a 95.2 g sample
of the compound contains 40.8 g of carbon and 54.4 g of oxygen?
3. What is the percentage composition of N2O4?
4. What is the percentage composition of a compound made from 28 grams of nitrogen and 32
grams of oxygen?
-1-
(2 x 6.9) + 16.0 = 29.8 g Li2O
13.8g Li / 29.8 Li2O = 46.3 % Lithium
16.0 g O / 29.8 g Li2O = 53.7 % Oxygen
mass = 95.2 g
40.8 g C / 95.2 g = 42.9 % Carbon
54.48 O / 95.2 g = 57.1 % Oxygen
(2 x 14.0) + (4 x 16.0) = 92.0
28.0 g N / 92.0 g N2O4 = 30.4 % N
64.0 g O / 92.0 g N2O4 = 69.6 % O
28 + 32 = 60 g
28 g N / 60 g x 100 = 46.6 % Nitrogen
32 g O / 60 g x 100 = 53.3 % Oxygen
