A spontaneous process is the time-evolution of a system in which it releases free energy (usually as heat) and moves to a lower, more thermodynamically stable energy state. The sign convention of changes in free energy follows the general convention for thermodynamic measurements, in which a release of free energy from the system corresponds to a negative change in free energy, but a positive change for the surroundings.
A spontaneous process is capable of proceeding in a given direction, as written or described, without needing to be driven by an outside source of energy. The term is used to refer to macro processes in which entropy increases; such as a smell diffusing in a room, ice melting in lukewarm water, salt dissolving in water, and iron rusting.
The laws of thermodynamics govern the direction of a spontaneous process, ensuring that if a sufficiently large number of individual interactions (like atoms colliding) are involved then the direction will always be in the direction of increased entropy (since entropy increase is a statistical phenomenon).
Read more about Spontaneous Process: Overview
Famous quotes containing the words spontaneous and/or process:
“They [creative children] ask more questions than most children. They’re usually spontaneous and enthusiastic. Their ideas are unique and occasionally strike other kids as weird. They’re independent. Not that they don’t care at all what other kids think, but they’re able to do their thing despite the fact that their peers may think it’s strange. And they have lots and lots of ideas.”
—Silvia Rimm (20th century)
“come peace or war, the progress of America and Europe
Becomes a long process of deterioration—”
—Robinson Jeffers (1887–1962)