Question

Why should Gibb's free energy be negative?

Answer 1

The reason for Gibb's free energy to be negative

1. When G is negative, the reaction is spontaneous and, can proceed in the forward direction but if the reaction is nonspontaneous it can proceed spontaneously in the reverse direction, and the reaction is non-spontaneous when Gibb's free energy is positive.
2. Therefore Gibb's free energy cannot be positive and should always be negative.
3. Gibb's free energy is the combination of the enthalpy and product of temperature and entropy together.

Mathematically,

$∆G=∆H-T\left(∆S\right)$

$$\begin{gathered} ∆G=Changeinthegibb\text{'}sfreeenergy \\ ∆H=Changeintheenthalpy \\ ∆S=Changeintheentropy \\ T=Temperatureinkelvin \end{gathered}$$

Hence, Gibb's free energy is negative.