Question

Define phase ,component and degree of freedom.

Answer 1

1. PHASE: A phase is defined as any homogenous, physically distinct and mechanically separable portion of a system, which is separated from other parts of the system by definite surface. Example:-

• In a freezing water system ice, water and water vapour are the three phases which are
physically distinct and homogenous.

2. COMPONENT: It is the smallest number of independent variable constituents taking part in
the state of equilibrium, by means of which the composition of each phase can be
expressed in the form of chemical equation .Example:-

• In water system the phases present are ice, water and water vapour. The composition of each phase can be expressed by a single component, H20 . Hence it is a one component system.

3. DEGREE OF FREEDOM: It is defined as the smallest number of independent variables such as pressure, temperature and concentration that must be specified in order to define completely the state of a system. Example:
• For a system consisting of water in contact with its vapour,

                                    `" Watert"_I↔"Water vapourg"_g` 
To define it completely, we have to state either temperature or pressure. Hence, the system is univariant or degree of freedom is one .