Question

Enthalpy of a reaction at 27^oC is 15 kJ mol^-1. The reaction will be feasible if entropy is

• A. 15 J mol^-1 K^-1
• B. -50 J mol^-1 K^-1
• C. Greater than 50 J mol^-1 K^-1
• D. Less than 50 J mol^-1 K^-1

Answer 1

Answer: (C)

$\Delta \text{G} < \Delta \text{H} - \text{T} \Delta \text{S}$ for spontaneous reaction
$\Delta \text{G} should be - \text{ve}$
$\text{T} \Delta \text{S} > \Delta \text{H}$
i.e., $3 0 0 \Delta \text{S} > \text{15000 J}$
$\Delta \text{S} > \text{50 J} \, \text{mol}^{\text{-1}} \, \, \text{K}^{\text{-1}}$