Question

At \(298\,K\), for the reaction \[ N_2(g)+3H_2(g)\rightleftharpoons 2NH_3(g) \] \[ \Delta H=-92.4\ \text{kJ} \] and \[ \log K_c=5.75. \] What is the entropy change \((\Delta S)\) (in J K\(^{-1}\)) for this reaction at the same temperature? \[ (R=8.3\ \text{J K}^{-1}\text{mol}^{-1}) \]

• A. \(-300\)
• B. \(-400\)
• C. \(-200\)
• D. \(-100\)

Hint:

Useful relations: \[ \Delta G=-RT\ln K \] \[ \Delta G=\Delta H-T\Delta S \] and \[ \ln K=2.303\log K. \] For the Haber process, entropy decreases because \[ 4\ \text{moles of gas} \rightarrow 2\ \text{moles of gas}. \]

Answer 1

The Correct Option is C