For a given chemical reaction A → B at 300K the free energy change...

Given chemical reaction:

$A\mathop{⟶}_{T = 300K}B [ \Delta G{]}_{P, T} = - 49 . 4kJ / mol$

${\Delta H}_{rxn} = 51 . 4kJ / mol$

${\Delta S}_{rxn} = ?$

$⇒$From the relation $[ \Delta G{]}_{P, T} = \Delta H - T \Delta S$

$⇒ {\Delta S}_{rxn} = \dfrac{{\Delta H}_{rxn} - [ \Delta G{]}_{P, T}}{T}$

$= \dfrac{[ 51 . 4 - ( - 49 . 4 ) ] \times 1000}{300}\dfrac{J}{molK}$

$⇒ {\Delta S}_{rxn} = 336\dfrac{J}{molK}$