CATALYSTSCatalysts are substances used to increase or decrease the rate of a chemical reaction. A catalyst is a substance that changes the rate of a chemical reaction but remains chemically unchanged at the end of the reaction. The word catalysts originally comes from the word catalysis meaning the change in the rate of a chemical reaction. Catalysts, unlike other substances, can participate in many chemical transformations but are never consumed by the reaction itself. This means that when a catalyst is added to two substances to increase the rate of reaction between them, the catalyst is not consumed and can be reused.([3]"Chem4Kids.com: Reactions: Catalysts and Inhibitors." ) For example, the decomposition of hydrogen peroxide; in this chemical reaction, manganese oxide can be used as a catalyst. Thanks to manganese oxide, the reaction will proceed faster but nevertheless, manganese oxide itself will not be consumed. Catalysts that speed up the reaction rate are called positive catalysts and those that slow down the reaction rate are called inhibitors or negative catalysts. Scientifically speaking, catalytic reactions are the fastest chemical reactions. The speed of the reaction depends on the frequency of physical contact of the two reactants. The more they collide, the more activation energy is produced and therefore the faster the reaction. However, even though catalysts are not consumed by the chemical reaction itself, they can be inhibited, destroyed, or deactivated. But catalysts nonetheless allow a suitable local environment to promote one or more chemical reactions to react. ([6]"The effect of catalysts on reaction rates." Chemguide) Technically, the importance of catalysts is...... middle of paper ...... ader's CHEM4KIDS.COM. Internet. October 08, 2011. .[4]Creative Chemistry - Fun activities, worksheets, games and review quizzes. Internet. October 8, 2011. [5] “Road pollution in Dubai among the worst in the world - ArabianBusiness.com. » Middle East business news, events and information on Gulf finance and industry - ArabianBusiness.com. Internet. October 8, 2011. [6] “The Effect of Catalysts on Reaction Rates.” » Chemguide: helping you understand chemistry - Main menu. Internet. October 8, 2011. [7] “Power gains thanks to a sports catalyst”. Car Tuning and Modified Cars - How to... Guides. Internet. October 8. 2011. .