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EEJ MAIN Chemistry QUESTION #7509
Question 1

The volume occupied by 4.75 g of acetylene gas (C$_2$H$_2$) at 50°C and 740 mmHg pressure is approximately _____ L.
$[R = 0.0826\ \text{L atm K}^{-1}\ \text{mol}^{-1}]$

  • 6 L✔️
  • 7 L
  • 5 L
  • 8 L
Correct Answer Explanation

Molar mass of C$_2$H$_2 = 2(12) + 2(1) = 26\ \text{g/mol}$

Moles $= \dfrac{4.75}{26} \approx 0.1827\ \text{mol}$

$T = 50 + 273 = 323\ \text{K}$

$P = \dfrac{740}{760}\ \text{atm} \approx 0.9737\ \text{atm}$

$V = \dfrac{nRT}{P} = \dfrac{0.1827 \times 0.0826 \times 323}{0.9737} \approx \dfrac{4.875}{0.9737} \approx \mathbf{6}\ \text{L}$