Question

For the homogeneous reaction $ xA+yB\rightleftharpoons lY+mZ $ $ \Delta H{}^\circ =-30\,kJ\,mo{{l}^{-1}} $ and $ \Delta S=-100\,JK\,mo{{l}^{-1}} $ At what temperature the reaction is at equilibrium?

• A. $ 50{}^\circ C $
• B. $ 250{}^\circ C $
• C. $ 100K $
• D. $ 27{}^\circ C $

Answer 1

Answer: (D)

For the homogeneous reaction $ xA+yB\rightleftharpoons lY+mZ $ $ \Delta H{}^\circ =-\,30\,kJ\,\text{mo}{{\text{l}}^{-1}}, $ $ \Delta S=-\,100\,J\,\text{mo}{{\text{l}}^{-1}}{{K}^{-1}} $ By using $ \Delta G=\Delta H-T\cdot \Delta S $ At equilibrium: $ \Delta G=0 $ $ \therefore $ $ \Delta H=T\cdot \Delta S $ $ T=\frac{\Delta H}{\Delta S}=\frac{-30\times {{10}^{3}}J\,mo{{l}^{-1}}}{-100\,J\,mo{{l}^{-1}}\,{{K}^{-1}}} $ $ T=300\,K $ $ =300-273=27{}^\circ C $