Question

Calculate the number of oxygen atoms in a 140,0 g sample of fron(III) oxide (Fe, 0).

Answer 1

Answer:

7.951 x 0²³atoms

Explanation:

Mass of Fe₃O₄ = 140g

Solution:

To find the number of oxygen atoms in iron(III) oxide, we first find the number of moles in the compound:

  Number of moles = $\frac{mass}{molar mass}$

   Molar mass of Fe₃O₄ = (3x56) + (4x64) = 168 + 256 =424g/mol

  Number of moles = $\frac{140}{424}$ = 0.33mole

 1 mole of an atom contains 6.02 x 10²³atoms

∴number of oxygen atoms in Fe₃O₄ = 4 x 0.33 x 6.02 x 10²³atoms

                                                           = 7.951 x 0²³atoms