Controlling chemical reactions Chapter 2 Section 3 Mr. Gardner

Key Concepts How is activation energy related to chemical reactions? What factors affect the rate of a chemical reaction?

Key Terms Activation energy Concentration Catlyst Enzyme Inhibitor

Energy and Reactions Activation energy: the minimum amount of enetgy needed to start a chemical reaction All chemical reactions need a certain amount of activation energy to get started. The formation of water. Endothermic and exothermic reactions Endothermic reactions need activation to get started, but they need energy to keep going. Exothermic reactions need activation energy, but the products have less energy than the reactants. This results in the release of heat.

Rate of Chemical Reactions Chemist Control rates of reactions by changing factors such as surface area, temperature, and concentrations, and by using substances called catalysts and inhibitors. Surface area: when a chunk of solid substance reacts with a liquid or gas, only the particles on the surface of the solid come into contact with the other reactant. Lets break the solid apart Temperature: when a substance is heated, the particles move faster which produces a faster reaction rate. Concentration: the amount of substance in a given volume. Increasing the concentration of the reactants supplies more particles to react. Catalysts: A material that increases the rate of a reaction by lowering the activation energy. Enzymes: biological catalyst Inhibitors: a material used to decrease the rate of a reaction.