How does a catalyst increase the rate of a reaction? It decreases the enthalpy change of the reaction. It lowers the potential energy of the reactants. It provides a lower activation energy for the reaction. It raises the potential energy of the products.

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chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.