Iron is obtained from the following ores: red iron ore Fe2O3 and magnetic iron ore Fe3O4. Which ore has the highest iron content?

Given: Fe2O3 and Fe3O4. Find: ω1 (Fe) – ?, ω2 (Fe) -?
Decision.
1. Mass fraction of iron in Fe2O3.
Mr (Fe2O3) = 2 • Ar (Fe) + 3 • Ar (O) = 2 • 56 + 3 • 16 = 160
ω1 (Fe) = (2 • Ar (Fe) / Mr (Fe2O3)) • 100% = (2 • 56: 160) • 100% = 70%
2. Mass fraction of iron in Fe3O4.
Mr (Fe3O4) = 3 • Ar (Fe) + 4 • Ar (O) = 3 • 56 + 4 • 16 = 232
ω2 (Fe) = (3 • Ar (Fe) / Mr (Fe3O4)) • 100% = (3 • 56: 232) • 100% = 72.4%
Answer: Fe3O4 contains more iron than Fe2O3.

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