For a chemical reaction to be spontaneous at all temperatures, which of the following conditions must be met? a. ΔS° > 0, ΔH° > 0 b. ΔS° > 0, ΔH° < 0 c. ΔS° < 0, ΔH° < 0 d. ΔS° 0 e. It is not possible for a reaction to be spontaneous at all temperatures.

b. ΔS° > 0, ΔH° < 0

Explanation:

According the equation of Gibb's free energy -

∆°G = ∆°H - T∆°S

∆°G = is the change in gibb's free energy

∆°H = is the change in enthalpy

T = temperature

∆°S = is the change in entropy.

And, the sign of the Δ°G, determines whether the reaction is Spontaneous or non - Spontaneous or at equilibrium,

i. e.,

if

Δ°G <0, the reaction is SpontaneousΔ°G> 0, the reaction is non - Spontaneous Δ°G = 0, the reaction is at equilibrium

The reaction has the value for ∆°H 0 i. e., positive

Now,

∆°G = ∆°H - T∆°S

= ( - ∆°H) - T ( + ∆°S)

= ( - ∆°H) - T (∆°S)

∆°G = negative

Hence,

Δ°G < 0, the reaction is Spontaneous.