Question Detail
Question
How many grams of MgCl₂ is needed to obtain 5.0 × 10²³ ions?
Correct Answer
Option B is the correct answer.
Detailed Explanation
Assuming the 'ions' refer to Mg²⁺ ions, moles of Mg²⁺ = (5.0 × 10²³) / (6.022 × 10²³) = 0.83 mol. Moles of MgCl₂ = same as moles of Mg²⁺ = 0.83 mol. Molar mass MgCl₂ ≈ 95.3 g/mol. Mass = 0.83 × 95.3 = 79.1 g ≈ 78.9 g.
Hint
Use Avogadro's number and the formula unit of MgCl₂.