Catalysis

Catalysis (/kəˈtælᵻsᵻs/) is the increase in the rate of a chemical reaction due to the participation of an additional substance called a catalyst (/ˈkætəlᵻst/). With a catalyst, reactions occur faster and require less activation energy. Because catalysts are not consumed in the catalyzed reaction, they can continue to catalyze the reaction of further quantities of reactant. Often only tiny amounts are required.

Technical perspective

In the presence of a catalyst, less free energy is required to reach the transition state, but the total free energy from reactants to products does not change. A catalyst may participate in multiple chemical transformations. The effect of a catalyst may vary due to the presence of other substances known as inhibitors or poisons (which reduce the catalytic activity) or promoters (which increase the activity). The opposite of a catalyst, a substance that reduces the rate of a reaction, is an inhibitor.

Catalyzed reactions have a lower activation energy (rate-limiting free energy of activation) than the corresponding uncatalyzed reaction, resulting in a higher reaction rate at the same temperature and for the same reactant concentrations. However, the detailed mechanics of catalysis is complex. Catalysts may affect the reaction environment favorably, or bind to the reagents to polarize bonds, e.g. acid catalysts for reactions of carbonyl compounds, or form specific intermediates that are not produced naturally, such as osmate esters in osmium tetroxide-catalyzed dihydroxylation of alkenes, or cause dissociation of reagents to reactive forms, such as chemisorbed hydrogen in catalytic hydrogenation.

Catalysts (The Spectacular Spider-Man)

"Catalysts" is the seventh episode of the animated television series The Spectacular Spider-Man, which is based on the comic book character Spider-Man, created by Stan Lee and Steve Ditko. The episode sees Spider-Man trying to stop the psychotic supervillain Green Goblin from bombing a dinner party filled with high-class New York citizens on the night of his school's big Fall Formal.

Written by Andrew Robinson and directed by the series' co-developer Victor Cook, "Catalysts" marked the first appearance of Green Goblin in the series. The villain's design followed the show's color scheme by emphasizing the color green and was based primarily on initial designs by Alex Ross for the character in the 2002 film Spider-Man. Performers Steven Blum and Vanessa Marshall began their roles as Green Goblin and Mary Jane Watson, respectively.

The episode originally broadcast on April 26, 2008, following repeat episodes of "Natural Selection" and "Competition." It is available on both the third volume DVD set for the series, as well as the complete season box set. It ranked as among the highest rated children's telecast the morning it aired and received a generally positive response from television critics. Green Goblin's appearance and new personality split critics, who felt that it was suitable but also strayed from his comic appearance.