Question

A 10.0 L flask contains 64 g of oxygen at 27°C. (Assume O₂ gas is behaving ideally). The pressure inside the flask in bar is (Given R = 0.0831 L bar K^-1 mol^-1)

• A. 2.5
• B. 498.6
• C. 49.8
• D. 4.9

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
We use the Ideal Gas Equation $PV = nRT$ to relate pressure, volume, and temperature.
Key Formula or Approach:
Moles ($n$) = $\frac{\text{Given Mass}}{\text{Molar Mass}}$
Pressure ($P$) = $\frac{nRT}{V}$
Step 2: Detailed Explanation:
Given:
Mass of $O_{2} = 64$ g
Molar mass of $O_{2} = 32$ g/mol
$n = \frac{64}{32} = 2$ moles
$V = 10.0$ L
$T = 27^{\circ}\text{C} = 27 + 273 = 300$ K
$R = 0.0831$ L bar $K^{-1}$ $mol^{-1}$
Calculation:
\[ P = \frac{2 \times 0.0831 \times 300}{10} \]
\[ P = \frac{2 \times 8.31 \times 3}{10} \]
\[ P = \frac{49.86}{10} \]
\[ P = 4.986 \text{ bar} \]
Step 3: Final Answer:
Rounding off, we get approximately $4.9$ bar. Option (4) is correct.