Question

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 1

Answer: The number of
`Fe^(2+)` ions in one molecule of hemoglobin are 4.

Step-by-step explanation:

According to mole concept:

1 mole of an element contains
`6.022* 10^(23)` number of atoms.

We are given:

Mass of 1 mole of hemoglobin =
`6.8* 10^4g`

• Using above equation:

`6.022* 10^(23)` number of molecules have a mass of
`6.8* 10^4g`

So, 1 molecule of hemoglobin will have a mass of
`(6.8* 10^4g)/(6.022* 10^(23))* 1=1.129* 10^(-19)g`

It is also given that 0.33 mass % of hemoglobin has
`Fe^(2+)` ions

So, mass of
`Fe^(2+)` ions will be =
`(0.33)/(100)* 1.129* 10^(-19)g=3.7257* 10^(-22)g`

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

`\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}`

Given mass of iron ion =
`3.7257* 10^(-22)g`

Molar mass of iron ion = 55.85 g/mol

Putting values in above equation, we get:

`\text{Moles of }Fe^(2+)\text{ ion}=(3.7257* 10^(-22)g)/(55.85g/mol)=6.67* 10^(-24)mol`

• Using mole concept:

1 mole of an element contains
`6.022* 10^(23)` number of atoms.

So,
`6.67* 10^(-24)` moles of hemoglobin will contain =
`6.022* 10^(23)* 6.67* 10^(-24)=4`

Hence, the number of
`Fe^(2+)` ions in one molecule of hemoglobin are 4.