# Separation Processes Questions and Answers – Phase Equilibria

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This set of Separation Processes Multiple Choice Questions & Answers (MCQs) focuses on “Phase Equilibria”.

1. How is the distribution among two or more phases at equilibrium determined by?
a) Application of entropy
b) Application of Newton’s laws of motion
c) Application of Gibbs free energy
d) Application of force

Explanation: G (T,P, N1, N2…..) is used to determine the extent of distribution in two or more phases.

2. At equilibrium the total Gibb’s free energy for all phases is
a) Minimum
b) Maximum
c) Infinity
d) Zero

Explanation: At equilibrium the total Gibbs’ free energies are minimum.

3. The chemical potential of a species is:
a) Different in all phases at chemical equilibrium
b) Same in all phases at chemical equilibrium
c) Different in all phases at physical equilibrium
d) Same In all phases at equilibrium

Explanation: µ i = µi (1) + µ i (2) …+ µ i (N) . Thus the chemical potential is same in all phases at physical equilibrium.

4. The formula for partial fugacity is:
a) F i =Cexp(µ i /RT)
b) F i = Cexp(µ i )
c) F i =exp(µ i )
d) F i =C(µ i /RT)

Explanation: The partial fugacity which is like pseudo pressure has a formula of F i =Cexp (µ i /RT).

5. What is the phase equilibrium ratio?
a) Ratio of heat of species in two phases at equilibrium
b) Ratio of temperature of species in two phases at equilibrium
c) Ratio of mole fractions of species in two phases at equilibrium
d) Ratio of equilibrium concentration of species in two phases at equilibrium.

Explanation: Phase equilibrium ratio is the ratio of mole fractions of species in two phases at equilibrium.

6. For a liquid-liquid case, what is phase equilibrium ratio?
a) Ratio of mole fractions of species in two phases at equilibrium
b) Ratio of distribution or partition coefficient
c) Ratio of equilibrium constant
d) Ratio of heat of supply

Explanation: K Di = x i (1) /x i (2).

7. Which equation is to be used for hydrocarbon and light gas mixture from cryogenic temperatures to critical region?
a) K i = ϕ iL / ϕ iV
b) K i = γ iL ϕiL/ ϕ iV
c) K i = P i s /P
d) K iiL P i s /P

Explanation: Here the equation of state is used.

8. Which equation is used for all mixtures from ambient to critical temperature?
a) K i = ϕ iL / ϕ iV
b) K i = γ iL ϕiL/ ϕ iV
c) K i = P i s /P
d) K iiL P i s /P

Explanation: Here the activity coefficient is also multiplied.

9. Which equation is used for ideal solutions at near ambient pressure?
a) K i = ϕ iL / ϕ iV
b) K i = γ iL ϕiL/ ϕ iV
c) K i = P i s /P
d) K iiL P i s /P

Explanation: Here, Roult’s law is used.

Sanfoundry Global Education & Learning Series – Separation Processes.

To practice all areas of Separation Processes, here is complete set of 1000+ Multiple Choice Questions and Answers. 