Question

Black iron (III) oxide solid can be converted into water and iron metal when it is reacted with hydrogen gas. If 125 g of iron (III) oxide reacted, how many moles of iron can be obtained?

Answer 1

Fe₂O₃ + 3H₂ → 2Fe + 3H₂O

M(Fe₂O₃) = 159.69 g/mol

n = m/M

n(Fe₂O₃) $= \frac{125}{159.69}=0.783\; mol$

n(Fe) = 2n(Fe₂O₃) $= 2\times 0.783 = 1.566 \;mol$

Answer: 1.56 mol