0.33% of iron (by weight) is present in hemoglobin (Molecular wt = 67200). The number of iron atom(s) in one m

Question

0.33% of iron (by weight) is present in hemoglobin (Molecular wt = 67200). The number of iron atom(s) in one molecule will be:

Accepted Answer

1. **Identify the Principle:** The mass percentage ($w/w$) of a component in a solution (or compound) is defined as the mass of the component divided by the total mass multiplied by 100 [Class 12 Chemistry, Ch 1, Sec 1.2.1, Eq 1.1].
2. **Calculate Mass of Iron:**
   $$ 	ext{Mass of Iron} = \frac{	ext{Percentage} 	imes 	ext{Molecular Weight}}{100} $$
   $$ 	ext{Mass of Iron} = \frac{0.33 	imes 67200}{100} = 221.76 	ext{ u} $$
3. **Determine Number of Atoms:**
   The atomic mass of Iron (Fe) is approximately $56 	ext{ u}$ (standard data).
   $$ 	ext{Number of atoms} = \frac{	ext{Total Mass of Iron}}{	ext{Atomic Mass of Fe}} $$
   $$ n = \frac{221.76}{56} \approx 3.96 $$
   Rounding to the nearest whole number, there are 4 iron atoms per hemoglobin molecule.

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