Answer:
= 3.358 moles
Step-by-step explanation:
Iron react with oxygen to form iron(iii) oxide according to the following reaction;
4Fe(s) +3O2(g) → 4Fe2O3(S)
Moles of Iron in 250 g is;
= 250 g/55.845 g/mol
= 4.477 moles
Using mole ratio; Iron : oxygen = 4 : 3
Moles of oxygen gas = 4.477 × 3/4
= 3.358 moles
Therefore. it means 3.358 moles of oxygen gas are required to react with 250 g of iron to form iron (ii) oxide.