For a spontaneous process, the change in Gibbs function is equal to the

The Change in the Gibbs function can be given as,

$△\mathrm{G}$

△G is a measure of free energy since it represents the net energy that is accessible to perform meaningful work.
G is negative for a spontaneous process.

 i.e; $△\mathrm{G}<0$

Thus,

$\begin{array}{l}{\mathrm{\Delta S}}_{\text{total }}>0,\mathrm{So}\\ {\mathrm{T\Delta S}}_{\text{sys }}-{\mathrm{\Delta H}}_{\mathrm{sys}}>0\\ \Rightarrow \left({\mathrm{\Delta H}}_{\mathrm{sys}}-\mathrm{T}\mathrm{△}{\mathrm{S}}_{\mathrm{sys}}\right)<0\end{array}$

So, $\mathrm{\Delta G}=\mathrm{\Delta H}-\mathrm{T\Delta S}<0$