Question: 83: A 10.0 L flask contains 64 g of oxygen at 27^{\circ}\mathrm{C}. (Assume \mathrm{O}_{2} gas is behaving ideally). The pressure inside the flask in bar is (Given \mathrm{R}=0.0831\,\mathrm{L}\,\mathrm{bar}\,\mathrm{K}^{-1}\,\mathrm{mol}^{-1} )
(1) 49.8
(2) 4.9
(3) 2.5
(4) 498.6
Answer: Option (2)
Explanation:
First, calculate the number of moles of oxygen gas present.
Molar mass of \mathrm{O}_{2} is 32\,\mathrm{g\,mol^{-1}}.
Number of moles n=\frac{64}{32}=2 mol.
Temperature in kelvin is 27+273=300\,\mathrm{K}.
Using the ideal gas equation PV=nRT.
Rearranging, P=\frac{nRT}{V}.
Substituting the values,
P=\frac{2\times0.0831\times300}{10.0}.
P=\frac{49.86}{10}.
P=4.986\,\mathrm{bar}.
Rounding to one decimal place, the pressure inside the flask is approximately 4.9\,\mathrm{bar}.
Hence, the correct answer is Option (2).