Hemoglobin, the oxygen-carrying protein in red blood cells, has four iron atoms per molecules ad contains 0.340 percent iron by mass. calculate the molar mass of hemoglobin

Molar mass of a compound is the equivalent mass of the compound per mole of it. To determine the molar mass of hemoglobin, we need to know the mass and the number of moles that is present in a certain sample. We make use of the values given above.
Given
0.340 percent Fe = 0.340 g Fe / 100 g hemoglobin
4 atoms Fe per 1 molecule of hemoglobin

Solution:
4 atoms Fe per 1 molecule of hemoglobin ( 1 mol Fe / 6.022 x10^23 atoms Fe) ( 55 .85 g Fe/ 1 mol Fe ) ( 6.022x10^23 molecule hemoglobin / 1 mol hemoglobin ) = 223.4 g Fe / mol hemoglobin

Molar mass = (100 g hemoglobin / 0.340 g Fe) (223.4 g Fe / mol hemoglobin) = 65705.88 g/mol hemoglobin