The enthalpy and entropy of a reaction are -5.0 kJ/mol and -20 JK- 1 mol- 1 respectively and are independent of temperature. What is the highest temperature upto which the reaction is feasible?

Question

The enthalpy and entropy of a reaction are -5.0 kJ/mol and -20 JK- 1 mol- 1 respectively and are independent of temperature. What is the highest temperature upto which the reaction is feasible? (A) 250 K (B) 240 K (C) 275 K (D) 300 K

Tardigrade Admin · Accepted Answer

Both Δ H and Δ S are negative and, therefore, the given reaction will be spontaneous (.Δ G < 0.) if Δ H-TΔ S < 0 or -5.0 kJ-T(.-20 JK- 1.) < 0 or -5.0× 103 J+T(.20 JK- 1.) < 0 i.e., T < (5 × 1 03 J/20 J K- 1) < 250 K .

Q. The enthalpy and entropy of a reaction are $- 5.0 k J / m o l$ and $- 20 J K^{- 1} m o l^{- 1}$ respectively and are independent of temperature. What is the highest temperature upto which the reaction is feasible?

250 K

240 K

275 K

300 K

Both $Δ H$ and $Δ S$ are negative and, therefore, the given reaction will be spontaneous $(Δ G < 0)$ if

$Δ H - T Δ S < 0$

or $- 5.0 k J - T (- 20 J K^{- 1}) < 0$

or $- 5.0 \times 1 0^{3} J + T (20 J K^{- 1}) < 0$

i.e., $T < \frac{5 \times 1 0 ^{3} J}{20 J K ^{- 1}} < 250 K$ .

Q. The enthalpy and entropy of a reaction are −5.0kJ/mol and −20JK−1mol−1 respectively and are independent of temperature. What is the highest temperature upto which the reaction is feasible?