Lesson: Chapter 7 — Quantification of Elements and Compounds

Working with moles 2 of 10 Reset answers

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Question 2

What amount of magnesium, in moles, is contained in 12 g of it? (Molar mass: Mg = 24 g mol^-1)

A 0.5 mol B 0.83 mol C 288 mol D 2 mol

The right answer is the one marked above.

0.5 mol. n = 12 g ÷ 24 g mol^-1 = 0.5 mol.

2 mol comes from inverting the division and taking 24 ÷ 12. The mass is less than the molar mass, so the answer must be below 1.

Answer the question to continue.