Question

Haemoglobin contains \(0.34\%\) of iron by mass. The number of Fe atoms in \(3.3\) g of haemoglobin is(Given: Atomic mass of Fe is \(56\) u, \(N_A\) = \(6.022 × 1023\) \(mol^{–1}\))

• A. \(1.21 × 10^5\)
• B. \(12.0 × 10^{16}\)
• C. \(1.21 × 10^{20}\)
• D. \(3.4 × 10^{22}\)

Answer 1

The Correct Option is C

To determine the number of iron (Fe) atoms in 3.3 grams of haemoglobin, we need to follow the steps below:

1. First, calculate the amount of iron by mass in 3.3 grams of haemoglobin. Since haemoglobin contains \(0.34\%\) of iron by mass, the mass of iron in 3.3 grams of haemoglobin can be calculated as follows:

\(\text{Mass of Fe} = \frac{0.34}{100} \times 3.3\, \text{g} = 0.01122\, \text{g}\)

1. Next, we need to find the number of moles of Fe in 0.01122 grams. Using the formula:

\(\text{Number of moles of Fe} = \frac{\text{Mass of Fe}}{\text{Molar mass of Fe}} = \frac{0.01122}{56} = 0.000200357\, \text{mol}\)

1. Finally, calculate the number of iron atoms using Avogadro's number \(N_A = 6.022 \times 10^{23}\, \text{mol}^{-1}\):

\(\text{Number of Fe atoms} = 0.000200357 \times 6.022 \times 10^{23} = 1.207174 \times 10^{20}\)

Rounding off the result gives us approximately:

\(1.21 \times 10^{20}\)

Thus, the correct answer is \(1.21 \times 10^{20}\) Fe atoms in 3.3 grams of haemoglobin.

Therefore, the correct option is:

• \(1.21 \times 10^{20}\)