Chemical Engineering Thermodynamics - Study Mode

[#221] The free energy change for a chemical reaction is given by (where, K = equilibrium constant)
Correct Answer

(B) -RT lnK

Explanation

Solution: The free energy change for a chemical reaction in terms of equilibrium constant is given by. $$Delta {G^ circ } = - RTlnK$$ Since at equilibrium $$Delta G$$ of the reaction $$=0$$

[#222] All gases except __________ shows a cooling effect during throttling process at atmospheric temperature and pressure.
Correct Answer

(D) Hydrogen

Explanation

Solution: Since all the gases except $${H_2}$$ $$He$$ etc, have maximum inversion point greater than atmospheric (room) temperature cooling can take place by throttling if the initial conditions lie in a region where joule thomson coefficient is positive. But for $${H_2}$$ the maximum inversion point is very low so usually heating takes place by throttling. But if we do the decrease the temperature of $${H_2}$$ from room temperature to below the maximum inversion point temperature by some primary cooling techniques than there are chances where cooling of $${H_{2,gas}}$$ can be done by throttling.

[#223] For equilibrium process (i.e. reversible) in an isolated system
Correct Answer

(A) ds = 0

Explanation

Solution: Since in case of reversible or equilibrium process $$delta Q = TdS$$ xa0 and for isolated system $$delta Q = 0$$ So, $$dS=0$$

[#224] Which of the following decreases with increase in pressure?
Correct Answer

(A) Melting point of ice

Explanation

Solution: According to Le Chatlier's principle the system will react in such a way that it minimizes the effect of deviation from equilibrium. Since, ice has the more volume than water Equilibrium shifts towards water (less volume) side thereby, minimizing the effect of pressure and regaining a new equilibrium. So, we can say the melting point is reached fast or decreased.

[#225] At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero. This follows from the
Correct Answer

(A) Third law of thermodynamics

Explanation

Solution: The given is statement of third law of thermodynamics.