Define the term catalysis with suitable examples
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Answer:
Catalysis is defined as increasing the rate of a chemical reaction by introducing a catalyst. A catalyst, in turn, is a substance that is not consumed by the chemical reaction, but acts to lower its activation energy. In other words, a catalyst is both a reactant and product of a chemical reaction. Typically, only a very small quantity of catalyst is required in order to catalyze a reaction.
The SI unit for catalysis is the katal. This is a derived unit which is moles per second. When enzymes catalyze a reaction, the preferred unit is the enzyme unit. The effectiveness of a catalyst may be expressed using the turnover number (TON) or turnover frequency (TOF), which is TON per unit time.
Catalysis is a vital process in the chemical industry. It is estimated that 90% of commercially-produced chemicals are synthesized via catalytic process.
Sometimes the term "catalysis" is used to refer to a reaction in which a substance is consumed (e.g., base-catalyzed ester hydrolysis). According to the IUPAC, this is an incorrect usage of the term. In this situation, the substance added to the reaction should be called an activator rather than a catalyst.
Examples of Catalysts
A wide variety of chemicals may be used as catalysts. For chemical reactions that involve water, such as hydrolysis and dehydration, the proton acids are commonly used. Solids used as catalysts include zeolites, alumina, graphitic carbon, and nanoparticles. Transition metals (e.g., nickel) are most often used to catalyze redox reactions. Organic synthesis reactions may be catalyzed using noble metals or "late transition metals," such as platinum, gold, palladium, iridium, ruthenium, or rhodium.
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