(i) Write the equation which relates the number of phases, components and degree of freedom of a system in equilibrium.    

(ii) How many phases and components are there in a system consisting of:

(1) a mixture of O₂ and N₂ gases

(2) N₂ gas containing H₂O vapour

(3) a mixture of ice and water

(4) a mixture of powdered iron and sulphur

(5) a lump of solid iron (II) sulphide

Give a suitable explanation, in brief, for your answer.

(i) The Gibb’s phase rule equation given below related the number of phases, components

and the degree of freedom of a system in equilibrium.

F = C – P + 2

where F = Number of degrees of freedom,

C = Number of components,

P = Number of phases, and

= represents the temperature and pressure.

(ii) (1) Phases—one (gaseous), Components—two.

(2) Phases—one (gaseous), Components—two.

(3) Phases—two (solid and liquid), Components—one

(4) Phases—one (solid), Components—two

(5) Phases—one (solid), Components—one