JEE Main201910 Jan 2019Morning ShiftChemistryThermodynamics (C)Actual
A process has Δ H = 200   J   m o l - 1 and Δ S = 40   J K - 1 m o l - 1 . Out of the values given below choose the minimum temperature above which the process will be spontaneous:
Options
- A20 K
- B5 K
- C12 K
- D4 K
Correct answer
B. 5 K
Step-by-step solution
∆ G = ∆ H - T ∆ S ....... (Gibbs Helmholtz Equation) For a reaction to be spontaneous, ∆ G < 0 So, ∆ H - T ∆ S < 0 ∆ H < T ∆ S ∆ H ∆ S < T i.e. Minimum temp. should be ⇒ ∆ H ∆ S = 200 40 = 5 K