Chapter 19 Section 1 Rates of Reaction rate- measures the speed of any change that occurs within an interval of time rate = change/time -rates of chemical reactions can vary greatly ex- lighting a match vs. producing coal -Some reactions cannot be reversed ex- bike left outside to rust

collision theory- atoms, ions and molecules can react to form products when they collide provided they have enough kinetic energy -particles without enough kinetic energy will bounce apart when they collide producing no reaction -bonds holding molecules together can also break apart

activation energy- the minimum amount of energy that particles must have in order to react activated complex- the arrangement of atoms at the peak of the activation energy barrier -this is right before reactants go to product- very unstable *page 535 *called transition state- unstable intermediate structure that connects reactants to products -it is just as likely to form back to reactants as it is to form products

Factors Affecting Reaction Rates 1)Temperature -speeds up rate of reaction as temp increases -higher temp = more collisions 2)Concentration -increasing the # of particles will speed up rate -more particles = more collisions 3)Particle Size -decrease particle size increases rate -larger surface area = faster rate

4)Catalysts -a substance that speeds up a reactions without being used up enzymes- catalysts used in body processes inhibitor- substance that interferes with the action of a catalyst