An oxide of metal (M) has 40% by mass of oxygen. Metal M has a relative atomic mass of 24. The empirical formula of the oxide is:
Correct answer: C. MO
- A. M₂O
- B. M₂O₃
- C. MO
- D. M₃O₄
Explanation
Assuming a 100g sample, we have 40g O and 60g M. Converting to moles gives: 40g/16g/mol = 2.5 mol O, and 60g/24g/mol = 2.5 mol M. The mole ratio of M:O is 2.5:2.5, which simplifies to 1:1. The empirical formula is MO.
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Mole calculations connect mass, number of particles and Avogadro's number, while balanced equations provide the mole ratios used in stoichiometry. Questions cover limiting and excess reactants, theoretical yield and percentage yield, including identifying which reactant is consumed first and comparing the actual product with the maximum possible product.
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