Does a spontaneous reaction mean that negative ∆G?

Question

Lilyana Simon · Accepted Answer

Gibbs free energy is defined as the thermodynamic potential that, in a thermodynamically closed system, may evaluate the maximum amount of work at constant temperature and pressure. Negative Free energy from Gibbs

(∆ G rxn)

means that the reaction is spontaneous and positive Gibbs free energy

(∆ G rxn)

indicates that process is nonspontaneous. When

∆ G = 0

, it indicates that equilibrium is achieved. Mathematically, we can write-

∆ G rxn = ∆ H rxn - T ∆ S rxn

, where-

∆ G rxn

is the Gibbs free energy change for a reaction,

∆ H rxn

is the enthalpy change for a reaction,

T

is the temperature and

∆ S rxn

is the entropy change for the reaction.When a reaction is exothermic

∆ H rxn < 0

and entropy change in the reaction is positive

(∆ S rxn > 0)

, we get

∆ G rxn < 0

which means a spontaneous reaction.
Negative

∆ G

hence indicates a spontaneous reaction.

Does a spontaneous reaction mean that negative /_\G?

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