Reaction Rate A measure of the speed of any change that occurs within an interval of time Usually expressed as the amount of reactant changing per unit of time Ways to measure: Amount of precipitate produced/time Amount of gas produced/time (change in pressure) Change in color/time using a spectrophotometer

Collision Theory Reaction rates depend on the collisions of reacting particles The more collisions, the faster the reaction rate Molecules must collide with enough energy AND proper orientation

Factors Affecting Reaction Rates Nature of Reactants Surface Area Temperature Catalysts Concentration

Activation Energy Minimum amount of energy necessary for a reaction to occur It’s much like a roller coaster!

Activated Complex A high energy arrangement of reactant molecules It is a transition state that is neither product nor reactant Exists where energy is the greatest

Potential Energy Diagrams activated complex Hproducts Hreactants activation energy ∆H

Catalyzed Reaction