Generic potential energy diagram showing the effect of a catalyst in a hypothetical exergonic chemical reaction X + Y to give Z. The presence of the catalyst opens a different reaction pathway (shown in red) with a lower activation energy. The final result and the overall thermodynamics ΔG are the same.

In chemistry, a catalyst is a molecular substance that increases the rate of a chemical reaction without itself undergoing any permanent change. [1] Catalysts that speed the reaction are called positive catalysts. Catalysts that slow down the reaction are called negative catalysts or inhibitors. A related term is residence time, symbol τ (tau), being the average length of time a particle of reactant spends within a process vessel or in contact with a catalyst. [2]

History
The theory or postulate of the “catalytic force” of was proposed in 1836 Swedish chemist Jacob Berzelius.

Human chemistry

See main: Human catalyst

The identification of what constitutes a “catalyst” in the process of a human chemical reaction is an advanced subject. The basic model, however, divides the matter of the biosphere into divisional categories: of reactive matter (e.g. human molecules), nutritive matter (e.g. an apple), substrate matter (e.g. the plot of land to a house), and catalytic matter (e.g. a television). [3] These tentative divisions, to note, serve only as crude guidelines, and where correctly each specific reaction must be studied in detail to determine the energy components effecting the human interactions.

In the study of the human chemical bond, for instance, the subject of secondary field particles, e.g. gold, as a type matter particle that transmits the force comes into play.

Steps of the Haber process, showing an iron surface (embedded with oxides) acting as a catalyst to the reaction of hydrogen with nitrogen to form ammonia. [4]

References
1. Daintith, John. (2004). Oxford Dictionary of Chemistry. Oxford University Press.
2. Licker, Mark D. (2003). Dictionary of Engineering, 2nd ed. New York: McGraw-Hill.
3. (a) Thims, Libb. (2007). Human Chemistry (Volume One) (Catalyst, pgs. 23, 33, 93, 95, 274, 312; Contact action, pg. 95; contact processes, pg. 95; human catalyst, pg. 23; negative catalyst, pg. 94; positive catalyst, pg. 94; catalytic closure, pg. 132; Definition: substrate, pg. 33; Section: substrate and catalysts, pgs. 93-98; Keyword: substrate, pgs. 18, 32, 38, 40, 73, 92-93, 96-99, 101, 107, 129, 140-41, 186, 259, 280, 304) (preview), (Google books). Morrisville, NC: LuLu.
(b) Thims, Libb. (2007). Human Chemistry (Volume Two), (preview), (Google books). Morrisville, NC: LuLu.
4. Chang, Raymond. (1998). Chemistry, (pgs. 540-41, 585). McGraw-Hill.

External links
● Catalysis – Wikipedia.