Chemical Engineering Thermodynamics MCQ Questions & Answers | Chemical Engineering

Clausius–Clapeyron equation is used during the phase change process and since the melting is a phase change process we can use it during the melting.

The kinetic energy of the molecules is Zero at absolute zero temperature (0K) as all the molecules will be at rest at this temperature.

We know the concept of fugacity is originated from the equation $$d{\mu _i} = pdv - sdT$$    for an pure gas.
Under constant temperature and assuming an ideal gas we can write this as $$d\mu = RTdlnP$$    and for an real gas the same equation is assumed keeping all the non-ideality in the term fugacity and written as $$d\mu = RTdlnf$$
So, we can say for an ideal gas $$f = p.$$

Lenz’s law is derived from law of conservation of energy.

From second law of thermodynamics
$$\eqalign{ & TdS \geqslant \delta Q \cr & \Rightarrow TdS \geqslant dU + \delta W \cr} $$
For an irreversible process $$S - dU - \delta W > 0.$$    So, system undergoing irreversible change under constant internal energy and constant volume will have entropy change greater than zero $$dS>0.$$
And for an reversible process $$TdS - dU - \delta W = 0.$$

Here if we see the situation with respect to a throttling process where reversible adiabatic expansion takes place there the heating or cooling takes place depending upon the initial conditions because there we have two contravening effects.
I. Increase in temperature due to viscous dissipation.
II. Decrease in temperature as the pressure energy of the gas is decreased.
But in case of reversible adiabatic compression we have same effect that means both the effects leads to increase in temperature only. Hence there will be heating.

The ideal behavior is usually shown at low pressures and high temperatures. One of the conclusion from this statement is that fugacity coefficient is one at low pressures.

Different gases will have different inversion temperatures usually the hydrogen and helium will have very low maximum inversion temperatures so, cooling by using throttling for these gases is slightly difficult.

At constant pressure the solubility of a gas increases with increase in temperature according to solubility rule.

During phase changes the temperature of the substances doesn’t increase instead the given thermal energy is used to break the intermolecular bonds and helps the substance to transfer from one phase to other phase. So, during this process the substance seems like an object having infinity thermal capacity because although we are transferring heat but the temperature is not raising.