Question

Haemoglobin contains $0.3465 \%$ of iron. One molecule of haemoglobin contains $4$ atoms of iron. The molecular mass of haemoglobin is_______ $kg\, mol ^{-1}$. (Atomic mass: $Fe =55.8\, u$ )

Answer 1

There are four atoms of iron in a molecule of haemoglobin.
Four atoms of iron contribute $0.3465 \%$ mass to a molecule of haemoglobin.
Mass of $4\, Fe =55.8 \times 4=223.2\, u =0.3465 \%$
Hence, $\frac{223.2}{x} \times 100=0.3465$
$\therefore x=\frac{223.2}{0.3465} \times 100=64416\, g\, mol ^{-1}$
$=64.42\, kg\, mol ^{-1}$