The sign and magnitude of Gibbs energy change of a chemical process tells about its spontaneity and useful work that could be extracted from it. Explain.

Explanation

To predict about the spontaneity of the reaction and
To predict the useful work that coulbe be extract is the sign and magnitude of the quantities in Gibbs equation is useful.
When a reaction is reversible it cannot proceed in both the direction with same case. In general the system would spontaneously change to configuration of lower free energy
At equilibrium `triangleG=0`
`O=triangleG^@+RT_(Lnk)`
`triangle_(r)G^@=-RT_(LnK)=-"2.303 RT log K"`
We know `triangle_(r)G^@= triangle_(r)H^@-T triangle_(r)S^@=-RT log K`
For endothermic reaction `triangle_r H^@` may be large and positive .
In such a case K is much less `(K lt 1)`
In exothermic reactions 4 Hº is large and negative `(K gt1) `
For exothermic reaction
a) K must be large
b) `triangleG^@` is highly negative
c) `triangleS^@` is highly positive
Hence with the sign and magnitude of the factors the yield of the product my be estimated.