Question

Calculate the percent composition by mass of oxygen in litharge (gram formula mss=223.2 grams per mole)

Answer 1

Litharge is a yellow oxide of lead with a formula of PbO, which is formed by heating lead metal in air.
The mass of one mole of PbO is 223.2 grams
1 mole of PbO contains 16 g of oxygen
Therefore; the percentage of oxygen will be;
(16/223.2) × 100 = 7.168 %

Answer 2

The % composition by mass of oxygen in litharge ( grams formula mass=223.2 g/mol) is calculated as below

% composition is percentage by mass of each element in a compound
which is calculated as follows

%composition = molar mass of element/molar mass of compound x100

The molar mass of oxygen = 16 g/mol

therefore the % composition = 16 g/mol/ 223.2 g/ mol x100 = 7.17 % of oxygen