Question

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 reduces 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 the r-butane with normal boiling point of 0°C.

Answer 1

Weight of butane in cylinder = 29.0 - 14.8

= 14. 2 kg

= 14.2 x 103 g

Molecular wt. of butane = 58,

p = 2.5 atm, T = 300 K

This is the volume of cylinder or volume of gas. Now the weight of gas left after use

= 23.2 - 14.8 = 8.4 kg = 8.4 x 103 g

The volume *** constant

Therefore, pressure (p) of gas left in cylinder= 1.48 atm

Now, pressure of gas given out = I

Weight of gas given out = 29.0 - 23.2

= 5.8 kg = 5.8 x 103g

Thus, volume of gas given out under these conditions is