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Hemoglobin, a protein in red blood cells, carries O2 from the lungs to the body's cells. Iron (as ferrous ion, Fe2+) makes up 0.33 mass % of hemoglobin. If the molar mass of hemoglobin is 6.8 × 104 g/mol, how many Fe2+ ions are in one molecule?

Answer :

Answer: The number of [tex]Fe^{2+}[/tex] ions in one molecule of hemoglobin are 4.

Explanation:

According to mole concept:

1 mole of an element contains [tex]6.022\times 10^{23}[/tex] number of atoms.

We are given:

Mass of 1 mole of hemoglobin = [tex]6.8\times 10^4g[/tex]

  • Using above equation:

[tex]6.022\times 10^{23}[/tex] number of molecules have a mass of [tex]6.8\times 10^4g[/tex]

So, 1 molecule of hemoglobin will have a mass of [tex]\frac{6.8\times 10^4g}{6.022\times 10^{23}}\times 1=1.129\times 10^{-19}g[/tex]

It is also given that 0.33 mass % of hemoglobin has [tex]Fe^{2+}[/tex] ions

So, mass of [tex]Fe^{2+}[/tex] ions will be = [tex]\frac{0.33}{100}\times 1.129\times 10^{-19}g=3.7257\times 10^{-22}g[/tex]

  • To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

Given mass of iron ion = [tex]3.7257\times 10^{-22}g[/tex]

Molar mass of iron ion = 55.85 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of }Fe^{2+}\text{ ion}=\frac{3.7257\times 10^{-22}g}{55.85g/mol}=6.67\times 10^{-24}mol[/tex]

  • Using mole concept:

1 mole of an element contains [tex]6.022\times 10^{23}[/tex] number of atoms.

So, [tex]6.67\times 10^{-24}[/tex] moles of hemoglobin will contain = [tex]6.022\times 10^{23}\times 6.67\times 10^{-24}=4[/tex]

Hence, the number of [tex]Fe^{2+}[/tex] ions in one molecule of hemoglobin are 4.

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