Question

Calculate the number of molecules and moles of \( \text{SO_2 \) in its 1.479 liters at STP.}

• A. \( 3.92 \times 10^{22}, 0.065 \)
• B. \( 3.92 \times 10^{23}, 0.65 \)
• C. \( 1.96 \times 10^{22}, 0.033 \)
• D. \( 1.96 \times 10^{23}, 0.33 \)

Answer 1

The Correct Option is A

Step 1: Use the ideal gas law to calculate moles.
At STP (Standard Temperature and Pressure), 1 mole of any ideal gas occupies 22.4 liters. The given volume of \( \text{SO}_2 \) is 1.479 liters, so the number of moles \( n \) of \( \text{SO}_2 \) can be calculated as follows: \[ n = \frac{\text{Volume}}{\text{Molar volume}} = \frac{1.479}{22.4} \approx 0.0659 \, \text{mol} \] Thus, the number of moles of \( \text{SO}_2 \) is approximately 0.065.
Step 2: Calculate the number of molecules using Avogadro's number.
The number of molecules in 1 mole of a substance is given by Avogadro's number, \( 6.022 \times 10^{23} \) molecules per mole. The number of molecules \( N \) in 0.065 moles of \( \text{SO}_2 \) is: \[ N = 0.065 \times 6.022 \times 10^{23} \approx 3.92 \times 10^{22} \, \text{molecules} \] Step 3: Conclusion.
The number of molecules of \( \text{SO}_2 \) is \( 3.92 \times 10^{22} \), and the number of moles is \( 0.065 \). This matches option (A).
\( 3.92 \times 10^{22}, 0.065 \)