An unsaturated solution of Na2SO4 is present in equilibrium

An unsaturated solution of Na2SO4 is present in equilibrium with its vapor in a closed vessel. (a) How many phases and components are present? (b) What is the number of degrees of freedom of the system? Identify the independent variables

Solution

No. of components = 2 (Na2SO4 and water - as each phase can be described by these two components only)

No. of phases = 3 ( solid and liquid and vapor)

degrees of freedom = 2-3+2 = 1