Question

Define the followings clearly - a. preferential liquefaction. b.fractional crystallisation

Answer 1

The processes are used for scientific, industrial and commercial purposes. Many gases can be put into a liquid state at normal atmospheric pressure by simple cooling; a few, such as carbon dioxide, require pressurization as well. Liquefactionis used for analyzing the fundamental properties of gas molecules (intermolecular forces), for storage of gases, for example:LPG, and in refrigeration and air conditioning. There the gas is liquefied in the condenser, where the heat of vaporization is released, and evaporated in the evaporator, where the heat of vaporization is absorbed. Ammonia was the first such refrigerant, and is still in widespread use in industrial refrigeration, but it has largely been replaced by compounds derived from petroleum andhalogens in residential and commercial applications.