Chemical Engineering Thermodynamics MCQ Questions & Answers | Chemical Engineering

During Throttling under adiabatic conditions the pressure energy decreases because some of the pressure energy gets lost as frictional losses thereby increase in intermolecular energy. Hence always there will be loss in pressure energy there by reducing the pressure.

Definition of $${C_V}$$ : when we add the heat to a system which is undergoing only expansion work or $$PdV$$ work at constant volume than the amount of heat required to raise the temperature by an infinitesimal amount is called as $${C_V}$$.

$${C_V} = \mathop {\lim }\limits_{\delta T \to \,0} \frac{{\partial Q}}{{\partial T}}$$

By first law of thermodynamics: $$\delta Q = dU + \delta W\left( {PdV} \right)$$     Since here $$dV=0$$
$$\delta Q = dU$$
So, $${C_V} = {\left( {\frac{{dU}}{{dT}}} \right)_V}.$$   Where $$U=$$  internal energy.

Kopp's rule states that the heat capacities of a molecular compound are sum of the contributions for each element in the compound. And it generally used to find the heat capacities of solids or liquid at $${20^{\text{o}}}C$$   for example the heat capacity of calcium chloride $$\left( {CaC{l_2}} \right)$$   can be written as heat capacity of $$Ca + {2\,\,*}$$   heat capacity of $$Cl$$ .

The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called as Boyle temperature.

A system which exchanges the energy but not mass is called as closed system or control mass system where the identity of mass also should remain same.

Activity $$\left( a \right)$$ of a pure ideal gas is defined as:

$$a = \frac{{{\text{fugacity at an temperature and pressure of interest}}}}{{{\text{fugacity at same temperature and standard pressure }}}}$$

usually the, standard pressure $$=$$ 1 atm and for ideal gas fugacity at a temperature and pressure $$=$$ pressure at that conditions
So, $$a=P$$

Eutectic point is a point where the homogeneous mixture will melt or solidifies at a same temperature which will be lower than the melting point of any of the constituents.

Since, phase rule is $$f\left( {{\text{degree of freedom}}} \right) = C - \emptyset + 2$$
Where, $$C=$$  number of components, $$\emptyset = $$  number of phases,
$$ \Rightarrow \emptyset = C - f + 2$$
So for maximum phases $$f$$ should be minimum $$f$$ cant be negative since it denotes number of variables hence $$f = 0$$
So, $$\emptyset = C + 2$$
Given $$C = X \Rightarrow \emptyset = X + 2$$

For an isobaric process the pressure remains constant.

For an ideal liquid solution the activity coefficient will be equal to 1. Since, activity coefficient of a species is defined as
\[{{\gamma }_{i}}=\frac{\text{fugacity of the species in the real solution}\left( \widetilde{{{f}_{l}}} \right)}{\text{fugacity of the species in the ideal solution}\left( \widetilde{{{f}_{l}}^{ld}} \right)}\]
For ideal solution \[\widetilde{{{f}_{l}}}=\widetilde{{{f}_{l}}^{ld}}\]
\[{\rm{So, }}{\gamma _i} = 1\]