Question

What happens when ΔH and ΔS are both positive?"

A) Reaction is spontaneous.
B) Reaction is non-spontaneous.
C) Depends on temperature.
D) Equilibrium is reached.

Answer 1

The spontaneity of a reaction where both ΔH and ΔS are positive depends on the temperature; the reaction is spontaneous at sufficiently high temperatures.

Step-by-step explanation:

When ΔH (change in enthalpy) and ΔS (change in entropy) are both positive, the spontaneity of the reaction depends on the temperature. The spontaneity is determined by the Gibbs free energy equation, which is ΔG = ΔH - TΔS, where T is the absolute temperature in Kelvin. A positive ΔH suggests an endothermic reaction, while a positive ΔS suggests an increase in disorder. For the reaction to be spontaneous, ΔG must be negative. This means that TΔS must be greater than ΔH for ΔG to be negative, indicating that the reaction is spontaneous at sufficiently high temperatures. Therefore, the correct answer to the question is C) Depends on temperature.