What occurs when Delta S is positive and Delta H is negative?

When Delta S, which represents the change in entropy, is positive, it indicates that the disorder or randomness of the system is increasing. A negative Delta H signifies that the process is exothermic, meaning that it releases heat to the surroundings.

In thermodynamics, the spontaneity of a process can be evaluated using the Gibbs free energy equation, which is given by:

[ \Delta G = \Delta H - T \Delta S ]

For a process to be spontaneous, the change in Gibbs free energy (Delta G) must be negative. When Delta H is negative, this contributes a negative value to Delta G. Additionally, having a positive Delta S (which, when multiplied by temperature, increases the value subtracted from Delta H) further promotes a negative Delta G, particularly at higher temperatures. Therefore, the combination of a negative Delta H and a positive Delta S results in a negative Delta G, indicating that the process is spontaneous.

This understanding is key to predicting the behavior of thermodynamic systems, especially when considering reactions or physical changes that occur naturally without external intervention. Thus, when Delta S is positive and Delta H is negative, the process is indeed spontaneous.