Question

Iron forms rust, expressed as: Fe2O3. Using information from the Periodic Table, what is the mass of one mole of Fe2O3?
A. 71.85 g
B. 143.70 g
C. 159.70 g
D. 319.40 g

Answer 1

It is C. 159.70 :) I just took the test.

Answer 2

Answer is: C. 159.70 g.

Balanced chemical reaction of forming rust: 4Fe + 3O₂ → 2Fe₂O₃.

The mass of the rusted nail, for example, equals the mass of iron and the oxygen from the air it reacted with to form the rust.

M(Fe₂O₃) = 2Ar(Fe) + 3Ar(O) · g/mol.

M(Fe₂O₃) = 2 · 55.85 + 3 · 16 · g/mol.

M(Fe₂O₃) = 111.7 + 48 · g/mol.

M(Fe₂O₃) = 159.7 g/mol; molar mass of iron(III) oxide.