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Spontaneous processes occur without any ongoing outside intervention and are irreversible.

Spontaneity Example

A process may be spontaneous at one temperature and non-spontaneous at another temperature. For example, imagine a glass of ice placed in a temperature-controlled room.

Spontaneity Temperature Example

In the first scenario, the room has a temperature above 0ยฐC (room temperature). In this room, the glass of ice will melt into liquid water (spontaneous process). In the second scenario, the room has a temperature below 0ยฐC. In this, room the glass of ice stays as a glass of ice unless you purposely heat up the glass to melt the ice (a non-spontaneous process because you added work).

Spontaneous processes may be either endothermic (energy absorbed from surroundings) or exothermic (energy released into surroundings).