Question

Determine which of the following statement is correct when the equilibrium constant K for a certain reaction is 10 at 298 K and 0.1 at 400 K?

1. The reaction is not spontaneous at any temperature if the standard entropy of reaction is positive.
2. The reaction is endothermic.
3. The reaction is not spontaneous at any temperature if the standard entropy of reaction is negative.
4. The reaction is spontaneous at any temperatures if the standard entropy of reaction is positive.
5. Cannot be determined without knowing what reaction that is.

Answer 1

4. The reaction is spontaneous at any temperatures if the standard entropy of reaction is positive.

Step-by-step explanation:

Equilibrium constant decreases on increasing the temperature . So the reaction appears to be exothermic . In other words

ΔH is negative .

Δ G = ΔH - TΔS

If ΔS is positive , second term is negative . ΔH is negative so the RHS of the equation is negative at all temperatures . Hence Δ G of the reaction is negative . So reaction is spontaneous at any temperature.