tailieunhanh - Chemical kinetics (chapter 13)

Chemical kinetics a study of the rates of chemical reactions | Chemical Kinetics Chapter 13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. PowerPoint Lecture Presentation by J. David Robertson University of Missouri a study of the rates of chemical reactions Chemical Kinetics Basically .How fast does a chemical reaction occur? Rates of Chemical Reactions Rate of a chemical reaction refers to the change in concentration of a substance per unit of time Let’s consider the rate at which you give me 3 dollars . your 3 dollars my 3 dollars Let’s say that it took you 5 seconds to give it to me. your 3 dollars my 3 dollars reactants products What is the rate of the reaction with respect to me [products]? Rate = change in concentration of money change in time Remember, change ( ) is always [ final – initial] Rate = + [3-0 dollars] [5-0 secs] Positive because I am the product which gains the money Rate = dollars/sec What is the rate with respect to you? Rate of reaction = - [0-3 dollars] [5-0 secs] Negative because you are the reactant and you are losing money Rate of reaction = dollars/sec ***Therefore, you can determine the rate of reaction either by using the reactants or the products. It will give you the same rate of reaction**** Let’s consider the rates for chemical reaction NO(g) + ½ O2 (g) NO2(g) Rate of the disappearance of NO: Rate = - [NO] t Rate of the disappearance of O2: Rate = - [O2] t Rate of the appearance of NO2: Rate = + [NO2] t A B rate = - D[A] Dt rate = D[B] Dt time If you know the rate of one species in a reaction you can determine the rate of any other species by the mole to mole ratio. Consider the previous reaction: NO(g) + ½ O2 (g) NO2(g) The nitrogen dioxide increases at a rate of mol/L •s. What is the rate of oxygen decreasing? mol NO2 L • sec x ½ mol O2 1 mol NO2 = mol O2/L • s NO(g) + ½ O2 (g) NO2(g) To determine the rate of reaction, you take the rate that you are given and divide by the stoichiometry in the . | Chemical Kinetics Chapter 13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. PowerPoint Lecture Presentation by J. David Robertson University of Missouri a study of the rates of chemical reactions Chemical Kinetics Basically .How fast does a chemical reaction occur? Rates of Chemical Reactions Rate of a chemical reaction refers to the change in concentration of a substance per unit of time Let’s consider the rate at which you give me 3 dollars . your 3 dollars my 3 dollars Let’s say that it took you 5 seconds to give it to me. your 3 dollars my 3 dollars reactants products What is the rate of the reaction with respect to me [products]? Rate = change in concentration of money change in time Remember, change ( ) is always [ final – initial] Rate = + [3-0 dollars] [5-0 secs] Positive because I am the product which gains the money Rate = dollars/sec What is the rate with respect to you? Rate of reaction = - [0-3 dollars] [5-0 secs] .