An oxide of iron has the formula Fe_3O_4. What is the mass percent of iron in Fe_3O_4?

• A. 55.8%
• B. 44.8%
• C. 65.0%
• D. 72.4%

Answer: (D)

Verified step by step guidance

1. Identify the chemical formula of the compound, which is Fe_3O_4. This means the compound contains 3 atoms of iron (Fe) and 4 atoms of oxygen (O).
2. Find the atomic masses of the elements involved: iron (Fe) has an atomic mass of approximately 55.8 g/mol, and oxygen (O) has an atomic mass of approximately 16.0 g/mol.
3. Calculate the total molar mass of Fe_3O_4 by multiplying the number of atoms of each element by their atomic masses and then summing these values: \(\text{Molar mass} = 3 \times 55.8 + 4 \times 16.0\).
4. Calculate the total mass of iron in one mole of Fe_3O_4 by multiplying the number of iron atoms by the atomic mass of iron: \(\text{Mass of Fe} = 3 \times 55.8\).
5. Determine the mass percent of iron in Fe_3O_4 using the formula: \(\text{Mass \% Fe} = \left( \frac{\text{Mass of Fe}}{\text{Molar mass of Fe}_3\text{O}_4} \right) \times 100\%\).