Chemical Reactions and Energy

Activation Energy (E A ) is the minimum amount of energy required for a reaction to take place EndothermicReaction Exothermic Reaction

Chemical Reactions that release energy are exergonic reactions Chemical Reactions that require more energy to break bonds than is released when new ones are formed are called endergonic reactions

Energy in reactions can be found in the forms of light, electricity and heat If the energy released from a reaction is heat then it is considered to be exothermic (heat packs and explosions) If the energy absorbed from a reaction is heat then it is endergonic (ex. Cold packs)

Electroplating is an endergonic reaction that requires electricity (gold plated jewelry and plated coins)

Catalysts and Inhibitors Some reactions proceed too slowly to be useful. In these cases a catalyst can be added to speed them up A catalyst speeds up a reaction without being permanently changed itself

Some reactions are not desirable and an inhibitor is used. Inhibitors tie up reactants and prevent them from undergoing the original reaction An example is food preservatives to prevent the spoilage of food Lemon juice is an excellent inhibitor to keep fruits from turning colors Inhibitors and Catalysts do not change the amount of product produced just the rate at which it is produced