For a given chemical reaction \( A \rightarrow B \) at \( 300 \, \text{K} \) the free energy change is \( -49.4 \, \text{kJ mol}^{-1} \) and the enthalpy of reaction is \( 51.4 \, \text{kJ mol}^{-1} \). The entropy change of the reaction is __________ \( \text{J K}^{-1} \text{ mol}^{-1} \).