The empirical formula of a metal oxide is M ₂ O ₃ . If the metal M constitutes 70 % of the mass of the oxide, what is the atomic mass of M ? (Given: Atomic mass of O = 16 amu )

Step-by-step solution

Let the atomic mass of the metal M be A_ M . The mass percentage of oxygen in the oxide is 100 % - 70 % = 30 % . The ratio of the number of moles of M to the number of moles of O is given by the empirical formula M ₂ O ₃ , which is 2:3 . Therefore, we can write: Moles of M Moles of O = 2 3 Substituting the mass percentages and atomic masses: 70 A_ M 30 16 = 2 3 70 16 30 A_ M = 2 3 112 3 A_ M = 2 3 A_ M = 112 3 3 2 = 56 The atomic mass of metal M is 56 amu . Answer: 56 amu