Question

For a reaction both enthalpy change and entropy change are positive . under what conditions the reaction will be spontaneous

Answer 1

When the absolute temperature is greater than ΔH/ΔS
For a reaction to be considered spontaneous, Gibbs free energy must be negative.

The equation for Gibb's free energy is ΔG=ΔH−TΔS, where:

ΔH = enthalpy change (kJ mol−1)

T = absolute temperature (K)

ΔS = entropy change (J K−1)

So, here we have: ΔG=ΔH−TΔS

ΔG<0 for a reaction to be considered spontaneus.

So, we have: ΔH−TΔS<0

ΔH<TΔS

T>ΔHΔS

Answer 2

Answer:

Let us consider the equation for gibbs free energy

ΔG=ΔH−TΔS

Where,

∆H is enthalpy change (KJmol−1 )

T is absolute temperature (K)

ΔS is entropy change (JK −1 )

For a reaction to be considered spontaneous ΔG<0

Therefore,

ΔH−TΔS<0

ΔH<TΔS

or

T>ΔHΔS