Question

Haemoglobin contains $0.25$% iron by mass. The molecular mass of haemoglobin is $89600$. Calculate the number of iron atoms per molecule of haemoglobin. (Atomic mass $Fe=56$)

Answer 1

$\because 100g$ haemoglobin has iron $=0.25g$

$\therefore 89600g$ haemoglobin has iron $=\frac{0.25\times 89600}{100}=224gFe$

1 mole or N molecules of haemoglobin has $224gFe=\left(224/56\right)g-atomofFe$

$=4g-atomofFe$

$=4NatomofFe$

1 molecule of haemoglobin $=4$ atom of $Fe$