The chapters in this section deal with the rates and mechanisms of chemical change. These topics stand in contrast to the subjects of equilibrium and thermodynamics that control the direction of chemical change. Chemical change is guided and driven by energetics (thermodynamics), but the actual route it takes and the speed with which it occurs is the subject of "dynamics". Dynamics is itself divided into two general areas: kinetics, which deals with the rate of change and is the subject of this lesson. Mechanistics, introduced in a later lesson, is an exploration of the "road map" that links reactants to products. 17.1: Rates of reactions and rate laws Chemical change is guided and driven by energetics, but the actual route it takes and the speed with which it occurs is the subject of "dynamics". Dynamics is itself divided into two general areas: kinetics, which deals with the rate of change and is the subject of this lesson. Mechanistics, introduced in a later lesson, is an exploration of the "road map" that links reactants to products. The energetic aspects of change are governed by the laws of thermodynamics. 17.2: Reaction Rates Typically Change with Time On this page we extend the concept of differential rate laws introduced on the previous page to integral rate laws and reaction half-life that are of great importance in most practical applications of kinetics. 17.3: Collision and activation- the Arrhenius law Why are some reactions so much faster than others, and why are reaction rates independent of the thermodynamic tendency of the reaction to take place? These are the central questions we address in this unit. In doing so, we open the door to the important topic of reaction mechanisms: what happens at the microscopic level when chemical reactions take place? To keep things as simple as possible, we will restrict ourselves to reactions that take place in the gas phase. 17.4: Reaction Mechanisms The mechanism of a chemical reaction is the sequence of actual events that take place as reactant molecules are converted into products. Each of these events constitutes an elementary step that can be represented as a coming-together of discrete particles ("collision") or as the breaking-up of a molecule ("dissociation") into simpler units. 17.5: Kinetics of Reactions in Solution The kinetics fundamentals we covered in the earlier sections of this lesson group relate to processes that take place in the gas phase. But chemists and biochemists are generally much more concerned with solutions. This lesson will take you through some of the extensions of basic kinetics that you need in order to understand the major changes that occur when reactions take place in liquid solutions. 17.6: Catalysts and Catalysis Catalysts play an essential role in our modern industrial economy, in our stewardship of the environment, and in all biological processes. This lesson will give you a glimpse into the wonderful world of catalysts, helping you to understand what they are and how they work. 17.7: Experimental methods of chemical kinetics Studies of the dynamics of chemical processes impinge on almost every area of chemistry and biochemistry. It is useful for students even at the general chemistry level to have some understanding of the experimental techniques that have informed what you have already learned about kinetics.