Answer:
Identify the "given" information and what the problem is asking you to "find."
Given : Cl2O7
Find: % Composition (% Cl and %O)
List other known quantities.
Mass of Cl in 1 mol Cl2O7 , 2 Cl : 2 x 35.45 g = 70.90 g
Mass of O in 1 mol Cl2O7 , 7 O: 7 x 16.00 g = 112.00 g
Molar mass of Cl2O7 = 182.90 g/mol
