An LPG (liquified petroleum gas) 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°C, the weight of the full cylinder is reduced to 23.2 kg. Find out the volume of the gas in cubic metres used up at the normal usage conditions and the final pressure inside the cylinder. Assume LPG to be n-butane with normal boiling point of 0°C.

An LPG (liquified petroleum gas) cylinder weighs 14.8 kg when empty. W

1.	An LPG (liquified petroleum gas) 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°C, the weight of the full cylinder is reduced to 23.2 kg. Find out the volume of the gas in cubic metres used up at the normal usage conditions and the final pressure inside the cylinder. Assume LPG to be n-butane with normal boiling point of 0°C.
Answer» ting the volume of gas:Given,i) Weight of cylinder with gas = 29.0 kgii) Weight of empty cylinder = 14.8 kgTherefore, the weight of gas in the cylinder = 29.0 - 14.8 = 14.2 kgPressure in cylinder = 2.5 atmTherefore, NUMBER of moles (n) in 14.2 KG (14.2 × g) of butaneWe KNOW that, n = 244.83 molApplying gas equation, V = 2412 LITERS[27°C = 273 + 27 = 300]Calculating the pressure in cylinder after use:i) Weight of cylinder after use = 23.2 kgii) Weight of empty cylinder = 14.8 kgTherefore weight of unused gas = 8.4 kg = 8.4 x g) moles of butaneWe know that, P = 1.478 atm[V = 2412 L]Calculating the volume of USED gas at 2.5 atm and 27°CWeight of the used gas = 14.2 - 8.4 = 5.8 kgPressure under normal usage conditions = 1 atm= 246 litersV = 2.463