A compound is found to contain 30.7% Sulfur, 23,3% Magnesium and 46% Oxygen. What is the empirical formula of the compound?

A Level
  1. Change % of elements in to moles: 30.7 mol of S, 23.3 mol of Mg and 46 mol of O2.
  2. Find the mass of each of the elements: 30.7 mol / 32.06 g/mol = 0.96 g of S;  23.3 mol / 24.31 g/mol = 0.96 g of Mg;  46 mol / 16.00 g/mol = 2.88 g of O2;  
  3. Divide the masses by the smallest mass: 0.96/0.96 = 1; 0.96/0.96 = 1; 2.88/0.96 = 3
  4. The empirical formula of this compound is MgSO3. 

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