Question

Haemoglobin contains 0.33% of iron by weight. The molecular weight of haemoglobin is approximately 67200 g. The number of iron atoms (at. weight of Fe is 56) present in one molecule of haemoglobin are

• A. 1
• B. 6
• C. 4
• D. 2

Answer 1

The Correct Option is C

The problem involves determining the number of iron (Fe) atoms in a molecule of haemoglobin. We are given that haemoglobin contains 0.33% iron by weight, and the molecular weight of haemoglobin is approximately 67200 g. The atomic weight of iron (Fe) is 56.

To find out the number of iron atoms present in one molecule of haemoglobin, we can follow these steps:

1. Calculate the total mass of iron in one mole of haemoglobin:

\(\text{Mass of iron in haemoglobin} = \frac{0.33}{100} \times 67200 \, \text{g}\)

2. Solve the above equation to find the mass of iron:

\(\text{Mass of iron} = \frac{0.33}{100} \times 67200 = 221.76 \, \text{g}\)

3. Next, calculate the number of moles of iron in the haemoglobin using its atomic weight:

\(\text{Number of moles of Fe} = \frac{\text{Mass of Fe}}{\text{Atomic weight of Fe}}\)

= \(\frac{221.76}{56} \approx 3.96\)

4. This calculated number (approximately 3.96) is very close to 4, implying that there are 4 iron atoms in one molecule of haemoglobin.

Thus, the number of iron atoms in one molecule of haemoglobin is 4.

Therefore, the correct answer is:

4