Hemoglobin, the oxygen-carrying protein in red blood cell, has 4 iron atoms per molecule and contains 0.40 % iron by mass. Calculate the molar mass of hemoglobin.
Solution: The mass of Fe on the Periodic Table is 55.845 g/mol
Let's calculate the mass of of 4 atoms of Fe.
55.845 g/mol * (1mol) * ( 4 atoms) = 3.7 *10^-22 grams
6.02*10^23 atoms
3.7 *10^-22 grams = 0.40 % iron by mass. Let's calculate the mass of one molecule.
3.7 *10^-22 grams = 9.277 g in 1 molecule of hemoglobin
0.0040
Now we need to convert, g/molecule to g/mol using Avogadro's number
9.277 g * 6.02*10^23 molecules = 55845 g/mol = 5.6*10^4g/mol
1molecule 1mol