Q.
For vaporization of water at 1 atmospheric pressure, the values of ΔH and ΔS are 40.63 kJ mol⁻¹ and 108.8 J K⁻¹ mol⁻¹, respectively. The temperature when Gibbs energy change (ΔG) for this transformation will be zero, is
A) 273.4 K
B) 393.4 K
C) 373.4 K
D) 293.4 K
Explanation
[Solution from source] ΔG = ΔH − TΔS = 0 gives T = ΔH/ΔS = 40630/108.8 = 373.4 K. Forgetting to convert kJ to J (or mixing units) gives nonsensical values; 373 K is also the normal boiling point of water, as expected. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.