Chemical Reactions

Chemical Reactions Chemical Reaction: process that changes one set of chemicals into another set of chemicals Reactants - elements or compounds entering the reaction Products - elements or compound formed by the reaction Break bonds in reactions and form new bonds in products CO2 + H2O  H2CO3 H2CO3  CO2 + H2O

Energy in Reactions Chemical reactions can release energy or absorb energy when chemical bonds are formed or broken. Reactions that release energy occur spontaneously. Heat, light, or sound Reactions that absorb energy need a source of energy to begin. 2H2 + O2 –> 2H2O

Activation Energy Activation Energy: energy need to start a reaction Cellulose, in paper, burns in the presence of oxygen and release heat and light, but requires the energy of match to start the reaction.  Catalysts: a substance that speed up the rate of chemical reactions; Lowers activation energy Use catalysts when activation energy is too great or reaction is too slow

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Enzymes Enzymes: protein catalyst that speed up reaction inside cells Specific: each enzyme only catalyzes only one reaction Each enzyme has a specific, complex shape names end in -ase

Enzyme Action Enzymes provide a site where reactant can come together to react  reduces energy need substrates: reactants of enzyme-catalyzed reaction substrate binds to the active site

Enzyme Action Regulation of Enzyme Activity lock & key: which have complementary shapes once the substrate binds to the enzyme, it becomes Enzyme-Substrate Complex they remain bound until the reaction occurs after which, the products are released the enzyme can start anew Regulation of Enzyme Activity affected by temperature & pH

Enzyme Animation http://www.lpscience.fatcow.com/jwanamaker/animations/Enzyme%20activity.html