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
View Answer
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
View Answer
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
View Answer
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)
View Answer
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.
View Answer
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
View Answer
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
View Answer
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
View Answer
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
View Answer
Explanation: Here, Roult’s law is used.