Question

Haemoglobin contains $0.25$% iron$\left(Fe\right)$ by mass. The molar mass of haemoglobin is $89600$ g/mole. The number $Fe$ atoms present in each molecule of haemoglobin is ________

Answer 1

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

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

$Fe=\frac{224}{56}$ mole $=4$ moles

$\therefore$ $1$ mole of haemoglobin has $4$ moles of Fe or $N_A$ molecule of haemoglobin has $4N_A$ atoms of Fe.

$\therefore$ 1 molecule of haemoglobin has 4 atoms of $Fe$.