A compound contains 60% Mg and 40% O by mass. The empirical formula of the compound is:
Correct answer: D. MgO
- A. Mg₂O₃
- B. MgO₂
- C. Mg₂O
- D. MgO
Explanation
Converting mass percentages to moles gives 2.5 mol Mg (60g/24g/mol) and 2.5 mol O (40g/16g/mol). The mole ratio of Mg:O is 2.5:2.5, which simplifies to 1:1. The empirical formula is MgO.
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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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