Question

Iron(iii) oxide is formed when iron combines with oxygen in the air. How many moles of Fe2O3 are formed when 55.8 g or Fe reacts completely with oxygen?
4Fe(s)+3O 2(g) --> 2Fe2O3(s)

A. 0.25 mol
B. 0. 50 mol
C. O. 75 mol
D. 1.00 mol

Answer 1

Answer: The correct answer is Option B.

Explanation:

To calculate the number of moles, we use the formula:

$Moles=\frac{\text{Given mass}}{\text{Molar mass}}$

• Moles of Iron

Molar mass of iron = 55.8 g/mol

Given mass of iron = 558.8

Putting values in above equation, we get:

$Moles=\frac{55.8g}{55.8g/mol}=1mole$

For the given chemical equation:

$4Fe(s)+3O_2(g)\rightarrow 2Fe_2O_3(s)$

By Stoichiometry,

4 moles of Iron produces 2 moles of Iron(III) oxide

So, 1 mole of Ion will produce = $\frac{2}{4}\times 1$ = 0.5 mole of Iron (III) oxide.

Hence, the correct answer is Option B.