Question

Why does a cooking gasbecome lighter after it has been used for few days?

Answer 1

• Cooking gas cylinders contain LPG (liquefied petroleum gas).
• When a cylinder is completely filled, its weight is maximum, as the fuel is in liquid form.
• However, since its boiling point is low, it quickly vaporises as we make use of it for cooking and the fuel gets expended.
• Thus, liquid evaporates and goes out of the cylinder gradually, as we use and finally, gets empty. This makes it light when the cylinder becomes empty.​
• Because it is lighter. The gas coming out is liquid inside the cylinder. And the liquid is heavy.
• The liquid instantly changes to a gas as it's released into the atmosphere, which is at a far lower pressure than inside the tank.