Question

A compound has haemoglobin like structure. It has one $Fe$. It contains $4.6\%$ of $Fe$. Determine its molecular mass.

Answer 1

We need to remember that the haemoglobin contains iron along with oxygen which is found in the red blood cells. Other than this it also contains other compounds as well. In the question we have an unknown compound with iron present in certain percent of the constituent compound. Concept of molar mass can be used to determine the moles, molar mass and other related information of an atom or of an atom present in molecules.

Complete step by step answer:
Let us assume the mass of the unknown compound to be $100g$ and the molar mass to be as $M$.
We know that the molar mass of iron atoms is $56g/mol$ and there is only one iron atom present in the unknown compound.
The percentage of iron in the unknown compound is given as $4.6\%$.
Now, the number of moles of the compound can be given by,
$\dfrac{{100}}{M}$
Now, if $56amu$ of iron is present in $100g$ of the compound (assumption), then,
$\dfrac{{4.6}}{{56}}amu$ of iron is present in $\dfrac{{100}}{M}g$ ,
Therefore,
$M = \dfrac{{100 \times 56}}{{4.6}} = 1217.39g$
Hence, the molecular mass of the unknown compound is $1217.39g$.

Note:
We must remember that the haemoglobin is a metallo-protein, an iron containing oxygen compound in the red blood cells. It is a protein in living bodies used to carry gases inside the body to various organs. It is not necessary that the haemoglobin only transports oxygen, it can also transport other gases depending upon the necessity of the living body. The mole concept has proved to be fruitful for analysis of the contents in various compositions. A substance may contain a number of atoms, molecules of various elements, but it can be easily and defined by the mole concept.