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

Hint: Haemoglobin is a protein that carries oxygen in our blood, it is present in red blood cells which gives red color to our blood. Iron is an essential element for blood production hence about seventy percent of the body's iron is present in Haemoglobin.

Complete step by step answer:
We have given that,
Haemoglobin contains $0.25\% $ iron by mass.
Atomic mass of Fe=$56$
The molecular mass of Haemoglobin=$89600$
So,
 Weight of iron per molecule of Haemoglobin= Mol. weight of Haemoglobin$ \times $ percentage of iron
Weight of iron per molecule of Haemoglobin=$89600 \times \dfrac{{0.25}}{{100}}$
Weight of iron per molecule of Haemoglobin=$224gm/mol$
Now we have obtained the weight of iron,, we will convert weight into moles.
Hence, Number of moles of iron =mass of iron/ molar mass of iron
Number of moles of iron =$\dfrac{{224}}{{56}}$=$4$
Hence in one mole of Haemoglobin we have four moles of iron that’s why one molecule of Haemoglobin has four atoms of iron.

Note:
To find out the number of atoms of a specific element in one molecule of any compound we find out the number of moles of element in one mole of a complex and this directly tells us the number of atoms in one molecule of the complex.