Intensive and extensive properties Trends

A spontaneous process is a natural process that occurs without any external input to the system. It releases free energy and moves the system to a lower, more thermodynamically stable energy state. The opposite of a spontaneous process is non-spontaneous, which requires an input of energy to occur. Examples of spontaneous processes include a ball rolling down an incline, water flowing downhill, and ice melting into water. The factors that determine spontaneity in a reaction are the enthalpy and entropy changes in the system. Spontaneous processes are important in thermodynamics, as they indicate the direction and behavior of chemical reactions.