What is the total number of oxygen atoms in 0.300 mol of iron(III) nitrate, Fe(NO3)3? (Avogadro constant = 6.02 × 10^23 mol^-1)
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Correct answer
A. 1.63 × 10^24
Principle or equation
Each formula unit of Fe(NO3)3 contains 3 nitrate ions, each with 3 oxygen atoms, so 9 oxygen atoms per formula unit. Multiply moles by Avogadro's number and by 9.
Why this answer is correct
Number of O atoms = 0.300 mol × 9 × 6.02 × 10^23 mol^-1 = 1.6254 × 10^24 ≈ 1.63 × 10^24.
Example
For 0.200 mol of Al2(SO4)3, O atoms = 0.200 × 12 × 6.02 × 10^23 = 1.44 × 10^24.
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