Spontaneous and Non-spontaneous Processes

A spontaneous process is a process that occurs in a system by itself; once started, no action from outside the system (outside agency) is necessary to make the process continue. A non-spontaneous process will not take place unless some external action is continuously applied.

Hot water kept in a container cools down by losing heat to the surroundings. The cooling down of hot water is an example of a spontaneous process. On the other hand, water at room temperature cannot become hot by gaining heat from the surroundings. It can be made hot by heating it over a gas burner. Heating of water (at room temperature) is an example of a non-spontaneous process because an outside agency (gas burner) has been used.

Properties

• If a process is spontaneous, the reverse process is non-spontaneous.

• Both spontaneous and non-spontaneous processes are possible.

• Spontaneous processes occur naturally whereas non-spontaneous processes require the help of an outside agency to occur.