Mini Lesson The rate law for kinetics is based on the law of mass action which states that: "The rate of a chemical reaction is directly proportional to the product of the concentrations of reacting substances, each raised to appropriate power" The general formula for a rate law is: R= K [A]* [B]* where= R is the reaction rate K is the rate constant A and B represent the molar concentrations of reactants The x and y are the representative powers to which the concentrations are raised, based on experimental data. Note: One cannot assume that the coefficients in the balanced equation for a net reaction are the exponents in the rate law for the reaction. The dependence of reaction rate on concentration of reactants was first recognized as a general principle of the law of mass action. In the rate law, the exponents of reactant concentrations are determined experimentally. A zero-order reaction has a rate that is independent of the concentration of the reactants. As such increasing or decreasing the concentration of the reacting species will not speed up or slow down the reaction rate. Example of a zero order reaction is the Haber process used to manufacture ammonia from hydrogen and nitrogen gas. First-order reaction: a reaction that depends on the concentration of only one reactant (unimolecular reaction). Other reactants can be presents, but each will be zero order Second-order reaction is a chemical reaction wherein the sum of the exponents in the corresponding rate law of the chemical reaction is equal to two. It can be understood that second order reactions are chemical reactions which depend on either the concentrations of two first-order reactants or the concentration of the second order reactant. Answer the following: 1. What is reaction rate? 2. Is change in temperature and introduction of a catalyst will affect the rate constant of a reaction? Why? For number 3-5, use the equation below to answer the questions H20 → 2H2 + O2 (assume reaction rate occurs at constant temperature) 3. Give the ra law 4. Write the overall order of the reaction 5. Find the rate, given K=1.14x10² and H20 concentration is 2.04Molar