Question

What does negative $∆\mathrm{G}$ mean?

Answer 1

1. In a chemical reaction with enthalpy and entropy change, it was not possible to predict whether it is a spontaneous or non-spontaneous process. Thus, a new term was coined “Gibbs free energy”.
2. Gibbs energy or Gibbs free energy is the quantity applied to measure the maximum quantity of work done when temperature and pressure are constant in a thermodynamic system.
3. It can be mathematically represented as follows:
   $∆\mathrm{G}=∆\mathrm{H}-\mathrm{T}∆\mathrm{S}$; where $∆\mathrm{G}$ is the change in Gibbs free energy, $∆\mathrm{H}$ is the change in enthalpy, T is the temperature, and $∆\mathrm{S}$is the change in entropy.
4. Change in Gibbs free energy will tell us the direction and the range of a chemical reaction.
5. If the change in Gibbs free energy is negative this signifies that the value $∆\mathrm{G}$ is less than 0.
6. If the value $∆\mathrm{G}$ is negative the reaction is spontaneous i.e. without any external or internal force the reaction can proceed.