Engineering Questions with Answers - Multiple Choice Questions

# Separation Processes MCQ’s – Phase Equilibria

1 - Question

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 - Question

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 - Question

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 - Question

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 - Question

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 - Question

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 - Question

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 i =γ iL P i s /P
Explanation: Here the equation of state is used.

8 - Question

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 i =γ iL P i s /P
Explanation: Here the activity coefficient is also multiplied.

9 - Question

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 i =γ iL P i s /P