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Chemical Engineering Thermodynamics MCQ Questions & Answers | Chemical Engineering

Learn Chemical Engineering Thermodynamics MCQ questions & answers are available for a Chemical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Chemical Engineering Thermodynamics MCQ question is the important chapter for a Chemical Engineering and GATE students. Page-7 section-5

Each section contains 100 MCQs on Chemical Engineering Thermodynamics .
61
The partial molar enthalpy of a component in an ideal binary gas mixture of composition Z, at a temperature T and pressure P, is a function only of
Discuss
Answer & Solution
Answer: Option B
No explanation is given for this question. Let's Discuss on Board
62
Which of the following behaves most closely like an ideal gas?
Discuss
Answer & Solution
Answer: Option A
Solution:
Helium acts more likely as ideal gas as it exists as an single atom which makes the vander waals dispersion forces as low as possible another factor is that it also consists of completely filled outer electron shell as a result, it has low tendency to react with other atoms.
63
The internal energy of a gas obeying P (V - b) RT (where, b is a positive constant and has a constant Cv), depends upon its
Discuss
Answer & Solution
Answer: Option C
Solution:
The internal energy of an gas is given by:
$$\eqalign{ & dU = CvdT - \left[ {P + T\left( {\frac{{\left( {\frac{{\partial V}}{{\partial T}}} \right)p}}{{\left( {\frac{{\partial V}}{{\partial P}}} \right)T}}} \right)dV} \right] \cr & \Rightarrow dU = CvdT + \left[ {T\left( {\frac{{\partial p}}{{\partial {T_V}}}} \right) - p} \right] \cr & {\text{using the given equation:}} \cr & P\left( {v - b} \right) = RT \cr & \Rightarrow \frac{{\partial P}}{{\partial T}} = \frac{R}{V} \cr & \Rightarrow dU = {c_v}dT \cr} $$
Hence internal energy is only a function of temperature.
64
Gibbs free energy of mixing at constant pressure and temperature is always
Discuss
Answer & Solution
Answer: Option D
Solution:
Change of Gibbs free energy due to mixing is given as $$\Delta {G_{mix}} = RT\sum {} xlnx$$     since mole fraction is always less than one we can say the change due to mixing is negative.
65
Heating of water under atmospheric pressure is an __________ process.
Discuss
Answer & Solution
Answer: Option B
Solution:
As we are heating at constant atmospheric pressure the process is isobaric.
66
Partial molar free energy of an element A in solution is same as its
Discuss
Answer & Solution
Answer: Option A
Solution:
The chemical potential is nothing but the partial molar Gibbs free energy.
$${\mu _i} = \left( {\frac{{\partial nG}}{{\partial {n_i}}}} \right)d{n_i}$$
By which we can tell whether the chemical equilibrium is reached by a system or not.
67
The absolute entropy for all crystalline substances at absolute zero temperature is
Discuss
Answer & Solution
Answer: Option A
Solution:
By third law of thermodynamics we can say for crystalline substances the absolute entropy is zero at absolute zero temperature.
68
Equilibrium constant decreases as the temperature
Discuss
Answer & Solution
Answer: Option A
Solution:
According to Le Chatelier's principle increase in temperature for an exothermic reaction will favor backward reaction and hence the product concentrations decreases and an new equilibrium is reached for an particular decrease in temperature and therefore the equilibrium constant decreases not increases.
$${K_C} = \frac{{C * D}}{{A * B}}$$
69
A solid is transformed into vapour without going to the liquid phase at
Discuss
Answer & Solution
Answer: Option A
Solution:
Sublimation occurs below the triple point and at the triple point the three phases co-exist at equilibrium.
70
The number of degrees of freedom at the triple point of water is
Discuss
Answer & Solution
Answer: Option A
Solution:
At triple point the number of phases $$= 3$$
Number of components $$= 1$$
So, degree of freedom $$f = C - \emptyset + 2 = 1 - 3 + 2 = 0$$