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

To determine the pressure inside the flask, we will use the ideal gas law equation: \( PV = nRT \). 
Here, \( P \) is the pressure, \( V \) is the volume, \( n \) is the number of moles, \( R \) is the ideal gas constant, and \( T \) is the temperature in Kelvin.
First, convert the mass of oxygen to moles. The molar mass of \( O_2 \) is approximately 32 g/mol.
\( n = \frac{64 \text{ g}}{32 \text{ g/mol}} = 2 \text{ mol} \)
Next, convert the temperature from Celsius to Kelvin: \( T = 27 + 273 = 300 \text{ K} \).
Now, substitute the known values into the ideal gas law: \[ P \cdot 10 \text{ L} = 2 \text{ mol} \times 0.0831 \text{ L bar K}^{-1} \text{ mol}^{-1} \times 300 \text{ K} \] \[ P \cdot 10 = 49.86 \text{ L bar} \] \[ P = \frac{49.86}{10} \] \[ P = 4.986 \text{ bar} \]
Rounding to one decimal place, the pressure is approximately 4.9 bar.