Chemical Engineering Thermodynamics MCQ Questions & Answers | Chemical Engineering

Since during the phase changes normally the temperature and pressure remains constant we call melting of ice an isothermal process.

Claude’s liquefaction process employs cooling of gas by expansion in engine.

A domestic refrigerator contains air as an cooled condenser.

Here the substance should be mentioned for which vaporization is taking place.

We know from second law of thermodynamics for an reversible process $$Tds = \delta Q$$
So, $$dS =0$$
When the process is adiabatic.
Hence for a reversible adiabatic process the entropy is constant.

The internal energy of an substance is given by
$$\eqalign{ & dU = CvdT - \left[ {P + T\left( {\frac{{\left( {\frac{{\partial V}}{{\partial T}}} \right)p}}{{\left( {\frac{{\partial V}}{{\partial P}}} \right)T}}} \right)dV} \right] \cr & {\text{For an ideal gas, }}PV = RT \cr & {\text{So, }}\left( {\frac{{\partial V}}{{\partial T}}} \right)p = \frac{R}{P}\,\,{\text{and }}\left( {\frac{{\partial V}}{{\partial P}}} \right)T = - \frac{{RT}}{{{P^2}}} \cr & {\text{Hence, }}dU = CvdT \cr} $$
So internal energy is only an function of temperature.

The gibbs free energy change as given by second law of thermodynamics goes on decreasing for an spontaneous irreversible process of constant temperature and pressure and finally when it is reached equilibrium the change is zero. Hence we can say a minimum exists for gibbs free energy.

The gibbs free energy change as given by second law of thermodynamics goes on decreasing for an spontaneous irreversible process of constant temperature and pressure and finally when it is reached equilibrium the change is zero. Hence we can say a minimum exists for gibbs free energy.