Question

The atomic mass of iron is 55.85, and oxygen is 16.0. What is the mass of 6.02 × 1023 molecules of Fe2O3?
A.
71.85 g
B.
143.7 g
C.
159.7 g
D.
199.55 g
E.
215.55 g

Answer 1

To determine the mass of 6.02 × 10²³ molecules of Fe₂O₃ (iron(III) oxide), we first need to calculate the molar mass of Fe₂O₃.

1. **Calculate the molar mass of Fe₂O₃:**

- Iron (Fe) has an atomic mass of approximately 55.85 g/mol. Since there are 2 iron atoms in Fe₂O₃:
\[
2 \times 55.85 = 111.7 \, \text{g/mol}
\]

- Oxygen (O) has an atomic mass of approximately 16.0 g/mol. Since there are 3 oxygen atoms in Fe₂O₃:
\[
3 \times 16.0 = 48.0 \, \text{g/mol}
\]

- Now, add the total masses together to find the molar mass of Fe₂O₃:
\[
111.7 \, \text{g/mol} + 48.0 \, \text{g/mol} = 159.7 \, \text{g/mol}
\]

2. **Now, since 6.02 × 10²³ molecules corresponds to 1 mole (Avogadro's number), the mass of 1 mole of Fe₂O₃ is:**
\[
159.7 \, \text{g}
\]

Given the options provided, the correct answer is:

**C. 159.7 g**