Engineering Questions with Answers - Multiple Choice Questions
Separation Processes MCQ’s – Liquid Activity Coefficient Models
1 - Question
Which model is used for predicting liquid-phase activity coefficients?
a) Entropy models
b) Enthalpy models
c) Gibb’s free equation model
d) Keller model
View Answer
Explanation: The model is based on change in Gibb’s free energy.
2 - Question
The relationship between excess molar free energy and excess molar enthalpy is:
a) GE = hE – TSE
b) GE = hE + TSE
c) GE = – TSE
d) GE = hE – T
View Answer
Explanation: The relationship between excess molar free energy and molar enthalpy is: GE = hE – TSE.
3 - Question
For a regular solution model what is the excess molar free enrgy dependent upon?
a) Volume occupied by molecules
b) Interaction of molecules
c) Molecular size and intermolecular forces
d) Enthalpy of formation of molecules
View Answer
Explanation: For a regular solution model what is the excess molar free energy dependent upon the Molecular size and intermolecular forces, the former expressed in terms of liquid molar volume and the later expressed in terms of enthalpy of vaporization.
4 - Question
Non-ideal solution effects can be incorporated in K-value formulations by:
a) Integrating for each molecule
b) Use of excess free energy
c) Use of enthalpy of vaporization
d) Use of partial fugacity coefficient ϕi
View Answer
Explanation: Non-ideal solution effects can be incorporated in K-value formulations by Use of partial fugacity coefficient ϕi.
5 - Question
In Margules equation, what is the one constant form equivalent to?
a) Unsymmetrical activity coefficient curves
b) Symmetrical activity coefficient curves
c) Similar partial fugacity coefficients
d) Dissimilar partial fugacity coefficients
View Answer
Explanation: In Margules equation, the one constant form equivalent to Symmetrical activity coefficient curves,which is rarely observed.
6 - Question
What is the temperature dependence of van laar constant?
a) Aij = A’ij/T
b) Aij = A’ijR/T
c) Aij = A’ij/TR
d) Aij = A’ij*RT
View Answer
7 - Question
When is Wilson’s equation superior to Margules and Van laar equation?
a) Non-ideal and immiscible mixtures
b) Ideal and miscible mixtures
c) Non-ideal and miscible mixtures
d) Ideal and immiscible mixtures.
View Answer
Explanation: Wilson’s equation superior to Margules and Van laar equation when the mixture is Non-ideal but miscible.
8 - Question
What is the full form of NRTL model?
a) No rational two liquid model
b) Non-random three liquid model
c) Non-random two liquid model
d) Non-Rating two liquid model
View Answer
Explanation: The NRTL model is non-random two liquid model.
9 - Question
How does the UNIQUAC model help?
a) It helps to place calculations of activity coefficients on practical basis
b) It helps to place calculations of activity coefficients on theoretical basis
c) It helps to place calculations of activity coefficients from graph
d) It helps to provide a easier way to place calculations
View Answer
Explanation: The UNIQUAC model depends on the theory to give the values of activity coefficients.
10 - Question
What must be true for two coexisting liquid phases?
a) YiL(1)xi(1) = YiL(2)xi(2)
b) YiL(1)xi(1) = xi(2)
c) YiL(1)xi(1)= YiL(2)yi(2)
d) YiL(1)xi(1) = XiL(2)xi(2)
View Answer
Explanation: For a liquid-liquid equilibria, for existence of two liquid phases, YiL(1)xi(1) = YiL(2)xi(2) must hold true.