Question

True or False? Please, explain.

(a) Since the three possible phases are solid, liquid, and gas, the max- imum possible value of the number of phases p in the phase rule is 3.

(b) The number of degrees of freedom f is the number of variables needed to specify the thermodynamic state of the system.

(c) The minimum possible value of f in the phase rule is 1.

(d) Along a line in a one-component phase diagram, f = 1.

(e) At the critical point of a pure substance, the densities of the liquid and the vapor are equal.

(f) The enthalpy of vaporization of a liquid becomes zero at critical point.

(g) The relation d lnP/dT ≈ ∆Hm/RT2 should not be applied near the critical point.

(h) Increasing the area of a liquid-vapor interface increases U of the system.

(i) The surface tension of a liquid goes to zero as the critical temper- ature is approached.

(j) When three phases coexist in equilibrium in a one-component sys- tem, one of the phases must be a gas, one must be a liquid, and one must be a solid.

Answer 1

(a) Since the three possible phases are solid, liquid, and gas, the maximum possible value of the number of phases p in the phase rule is 3.

ANSWER IS TRUE

BECAUSE P = 4 GIVES F=-1 which defines independent from variable, so does not exist in four phases

(b) The number of degrees of freedom f is the number of variables needed to specify the thermodynamic state of the system.

answer is true

(c) The minimum possible value of f in the phase rule is 1.

the answer is false

incase of P=3 F leads to zero which is seen in single component system at the triple point

(d) Along a line in a one-component phase diagram, f = 1

answer is true

C =1 P =2 (solid-liuid) f= 1-2+2