- published: 26 Aug 2010
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Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations. Catalysts that speed the reaction are called positive catalysts. Substances that slow a catalyst's effect in a chemical reaction are called inhibitors. Substances that increase the activity of catalysts are called promoters, and substances that deactivate catalysts are called catalytic poisons.
Catalytic reactions have a lower rate-limiting free energy of activation than the corresponding uncatalyzed reaction, resulting in higher reaction rate at the same temperature. However, the mechanistic explanation 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 lysis of reagents to reactive forms, such as atomic hydrogen in catalytic hydrogenation.
Siblings Carter and Jordyn are off to college, with aspirations of completing their life goals. For Carter, that means graduating at the top of his class and being accepted into the grad school of his choice. For Jordyn, it's discovering her true calling at college and grow as a person finally away from home. As brother and sister adjust to college life, it soon becomes apparent that they are growing apart. As Carter determines what he wants out of college, he starts to sacrifice his morals and ideals to achieve his goals. But Jordyn is finding college to be much tougher than she ever thought, forcing her to cope in ways she never imagined. Both learn the hard way: not everything works out in the end.
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