• # question_answer An LPG cylinder weighs 14.8 kg when empty. When full, it weighs 29.0 kg and shows a pressure of 2.5 atm. In the course of use at $27{}^\circ C$, the weight of the full cylinder is reduced to 23.2 kg. Find out the volume of n-butane in cubic meters used up at $27{}^\circ C$ and 1 atm. (Molecular weight of n-butane = 58).

Mass of n-butane used up = 29.0 - 23.2 = 5.8 kg No. of moles of n-butane used up$=\frac{5.8\times 1000g}{58\,g\,mo{{l}^{-1}}}\,=100$ To calculate volume of 100 moles of the gas at $27{}^\circ C$ and 1 atm pressure, apply$PV=nRT$ or $V=\frac{nRT}{P}=\frac{100\,mol\,\times 0.0821\,L\,atm\,{{K}^{-1}}\,mo{{l}^{-1}}\times 300K}{1\,atm}$ $=2463\,L=2\cdot 463\,{{m}^{3}}\,(1\,{{m}^{3}}={{10}^{3}}L)$