Question

2.40 g of iron reacts with oxygen gas to form 2.56 g of iron (Il) oxide.

How much oxygen reacted?

Answer 1

Stochiometry

Reaction

2Fe + O₂ ⇒ 2FeO

atomic mass Fe = 56 g/mol

molar mass FeO = 72 g/mol

moles of iron: 2.4 : 56 = 0.043

moles of FeO = 2.56 : 72 = 0.035

moles of FeO based on limiting reactant

because the coefficients of FeO and Fe are the same, then from the number of moles, Fe is an excess reactant

moles of oxygen: 1/2 x 0.035 = 0.0175

mass of oxygen: 0.0175 x 32 g/mol = 0.56 g