Question

Hemoglobin, an iron-containing oxygen-transport protein, is 0.349% Fe by mass.
If a hemoglobin molecule contains four iron atoms, what is the molar mass (in g/mol) of hemoglobin?

Answer 1

Answer : The molar mass of hemoglobin is, $6.40\times 10^4g/mol$

Explanation : Given,

Molar mass of iron = 55.85 g/mol

0.349 % Fe by mass that means 0.349 grams of Fe present in 100 grams of hemoglobin.

or,

$\text{Percent of Fe}=\frac{4\times \text{Molar mass of Fe}}{\text{molar mass of hemoglobin}}\times 100$

Now put all the given values in this formula, we get:

$0.349=\frac{4\times 55.85g/mol}{\text{molar mass of hemoglobin}}\times 100$

$\text{molar mass of hemoglobin}=64011.46g/mol=6.40\times 10^4g/mol$

Thus, the molar mass of hemoglobin is, $6.40\times 10^4g/mol$