Question

The molar mass of haemoglobin is about $65000$ g/mol. Haemoglobin contains $0.35$% Fe by mass. Thus, iron atoms present in haemoglobin molecules are _____.

Answer 1

The number of moles of Fe present in one mole of haemoglobin is $65000\text{g/mol haemoglobin}\times \frac{0.35\text{g iron}}{100\text{g haemoglobin}}\times \frac{\text{1 mol iron}}{55.8\text{g iron}}=4$ mol
Thus, $1$ mole of haemoglobin contains $4$ moles of Fe.
Hence, $1$ molecule of haemoglobin contains $4$ molecules of Fe.