Chapter 13.1-13.4 AP Chem Chemical Equilibrium Chapter 13 Table of Contents • • • • • • • 13.1 13.2 13.3 Pressures 13.4 13.5 Constant 13.6 13.7 Copyright © Cengage Learning.
Download ReportTranscript Chapter 13.1-13.4 AP Chem Chemical Equilibrium Chapter 13 Table of Contents • • • • • • • 13.1 13.2 13.3 Pressures 13.4 13.5 Constant 13.6 13.7 Copyright © Cengage Learning.
Chapter 13.1-13.4 AP Chem Chemical Equilibrium Chapter 13 Table of Contents • • • • • • • 13.1 13.2 13.3 Pressures 13.4 13.5 Constant 13.6 13.7 Copyright © Cengage Learning. All rights reserved The Equilibrium Condition The Equilibrium Constant Equilibrium Expressions Involving Heterogeneous Equilibria Applications of the Equilibrium Solving Equilibrium Problems Le Châtelier’s Principle 2 Chapter 13 Table of Contents • WEEK OUTLOOK • Monday - Notes 13.1-13.4 with problems w/sheet due Tuesday - should be able to complete in class today. • *Be sure all reports are turned in and made up TODAY! • Tuesday - Notes 13.5-13.7 with emphasis on Le Chatelier’s Principle emphasized & problems assigned due Wed. - some time in class to complete • Kaci & Jonathan - library 2nd floor 7:30 with ACT invent. • Wednesday- Lab • Thursday - CAPS - No class • Friday - Good Friday - No school • Tuesday - April 2nd - ACT Testing 11th graders only. • Test probably next Thursday - just over ch. 13 only. Copyright © Cengage Learning. All rights reserved 3 Chapter 13 Table of Contents • HANDOUTS - Ch. 13 NMSI Equilibrium Packet (Notes with practice problems) • HANDOUT - Equilibrium Homework Sheet #1 • TURN IN Kinetics Lab - will go over pre-lab questions • HW: Equilibrium w/s #1 should be done today - due Mon. for grade • HW: Notes packet #1-6 problems due next week but keep for studying. • CW: Notes 13.1-13.4 • VOTE ON KINETICS TESTING CH. 12 • Iodine Clock Rxn. Simulation Lab - as time permits Copyright © Cengage Learning. All rights reserved 4 5 Dynamic Nature of Equilibrium • When a system reaches equilibrium, the forward and reverse reactions continue to occur … but at equal rates. We are usually concerned with the situation after equilibrium is reached. After equilibrium the concentrations of reactants and products remain constant. Prentice Hall © 2005 General Chemistry 4th edition, Hill, Petrucci, McCreary, Perry Chapter Fourteen Section 13.1 The Equilibrium Condition Chemical Equilibrium • The state where the concentrations of all reactants and products remain constant with time. • On the molecular level, there is frantic activity. Equilibrium is not static, but is a highly dynamic situation. Return to TOC Copyright © Cengage Learning. All rights reserved 6 Section 13.1 The Equilibrium Condition Equilibrium Is: • Macroscopically static • Microscopically dynamic Return to TOC Copyright © Cengage Learning. All rights reserved 7 Section 13.1 The Equilibrium Condition Changes in Concentration • N2(g) + 3H2(g) 2NH3(g) Return to TOC Copyright © Cengage Learning. All rights reserved 8 Section 13.1 The Equilibrium Condition Chemical Equilibrium • Concentrations reach levels where the rate of the forward reaction equals the rate of the reverse reaction. Return to TOC Copyright © Cengage Learning. All rights reserved 9 Section 13.1 The Equilibrium Condition The Changes with Time in the Rates of Forward and Reverse Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 10 Section 13.1 The Equilibrium Condition Concept Check •Consider an equilibrium mixture in a closed vessel reacting according to the equation: • H2O(g) + CO(g) H2(g) + CO2(g) •You add more H2O(g) to the flask. How does the concentration of each chemical compare to its original concentration after equilibrium is reestablished? Justify your answer. Return to TOC Copyright © Cengage Learning. All rights reserved 11 Section 13.1 The Equilibrium Condition Concept Check •Consider an equilibrium mixture in a closed vessel reacting according to the equation: • H2O(g) + CO(g) H2(g) + CO2(g) •You add more H2 to the flask. How does the concentration of each chemical compare to its original concentration after equilibrium is reestablished? Justify your answer. Return to TOC Copyright © Cengage Learning. All rights reserved 12 Section 13.2 Atomic The Equilibrium Masses Constant Law of Mass Action Consider the following reaction at equilibrium: • jA + kB K= • • • • lC + mD l m j [A] [B]k [C] [D] A, B, C, and D = chemical species. Square brackets = concentrations of species at equilibrium. j, k, l, and m = coefficients in the balanced equation. K = equilibrium constant (given without units). Copyright © Cengage Learning. All rights reserved Return to TOC 13 Section 13.2 Atomic The Equilibrium Masses Constant Conclusions About the Equilibrium Expression • Equilibrium expression for a reaction is the reciprocal of that for the reaction written in reverse. • When balanced equation for a reaction is multiplied by a factor of n, the equilibrium expression for the new reaction is the original expression raised to the nth power; • thus Knew = (Koriginal)n. • K values are usually written without units. Return to TOC Copyright © Cengage Learning. All rights reserved 14 Conclusions about Equilibrium Expressions The equilibrium expression for a reaction is the reciprocal for a reaction written in reverse 2NO2(g) 2NO(g) + O2(g) 2NO(g) + O2(g) 2NO2(g) Conclusions about Equilibrium Expressions When the balanced equation for a reaction is multiplied by a factor n, the equilibrium expression for the new reaction is the original expression, raised to the nth power. 2NO2(g) 2NO(g) + O2(g) NO2(g) NO(g) + ½O2(g) Section 13.2 Atomic The Equilibrium Masses Constant • K always has the same value at a given temperature regardless of the amounts of reactants or products that are present initially. • For a reaction, at a given temperature, there are many equilibrium positions but only one value for K. Equilibrium position is a set of equilibrium concentrations. Return to TOC Copyright © Cengage Learning. All rights reserved 17 Section 13.3 The Mole Expressions Involving Pressures Equilibrium • K involves concentrations - (also called Kc) • Kp involves pressures for gases. Return to TOC Copyright © Cengage Learning. All rights reserved 18 Section 13.3 The Mole Expressions Involving Pressures Equilibrium Example • N2(g) + 3H2(g) 2NH3(g) Return to TOC Copyright © Cengage Learning. All rights reserved 19 Section 13.3 The Mole Expressions Involving Pressures Equilibrium Example • N2(g) + 3H2(g) 2NH3(g) • Equilibrium pressures at a certain temperature: Return to TOC Copyright © Cengage Learning. All rights reserved 20 Section 13.3 The Mole Expressions Involving Pressures Equilibrium Example • N2(g) + 3H2(g) 2NH3(g) Return to TOC Copyright © Cengage Learning. All rights reserved 21 Section 13.3 The Mole Expressions Involving Pressures Equilibrium The Relationship Between K and Kp • Kp = K(RT)Δn • Δn = sum of the coefficients of the gaseous products minus the sum of the coefficients of the gaseous reactants. • R = 0.08206 L·atm/mol·K • T = temperature (in kelvin) Return to TOC Copyright © Cengage Learning. All rights reserved 22 Section 13.3 The Mole Expressions Involving Pressures Equilibrium Example • N2(g) + 3H2(g) 2NH3(g) • Using the value of Kp (3.9 × 104) from the previous example, calculate the value of K at 35°C. Return to TOC Copyright © Cengage Learning. All rights reserved 23 Section 13.4 Heterogeneous Equilibria Homogeneous Equilibria • Homogeneous equilibria – involve the same phase: • N2(g) + 3H2(g) 2NH3(g) • HCN(aq) H+(aq) + CN-(aq) Return to TOC Copyright © Cengage Learning. All rights reserved 24 Section 13.4 Heterogeneous Equilibria Heterogeneous Equilibria • Heterogeneous equilibria – involve more than one phase: • 2KClO3(s) 2KCl(s) + 3O2(g) • 2H2O(l) 2H2(g) + O2(g) Return to TOC Copyright © Cengage Learning. All rights reserved 25 Section 13.4 Heterogeneous Equilibria • The position of a heterogeneous equilibrium does not depend on the amounts of pure solids or liquids present. The concentrations of pure liquids and solids are constant. – – 2KClO3(s) 2KCl(s) + 3O2(g) Return to TOC Copyright © Cengage Learning. All rights reserved 26 27 Equilibria Involving Pure Solids and Liquids • The equilibrium constant expression does not include terms for pure solid and liquid phases because their concentrations do not change in a reaction. • Example: Although the amounts of pure solid and CaCO3(s) CaO(s) + CO2(g) liquid phases change during a reaction, these phases remain pure and their [CaO] [CO ] 2 K = –––––––––– Kc = [CO2] c concentrations do not change. [CaCO ] 3 Prentice Hall © 2005 General Chemistry 4th edition, Hill, Petrucci, McCreary, Perry Chapter Fourteen Section 13.4 ASSIGNMENTS - 2/20/14 Heterogeneous Equilibria • W/sheet #1 problems due Monday • This assignment should be able to be completed today in class but is due Monday. • Ch. 13 Equilibrium packet - #1-#6 practice problems answers shown to see if you are doing correctly. • Prepare for Test on Kinetics. • HW: Read chapter 13 over the next week. • Ch. 12 Kinetics Test - VOTED for WEDNESDAY - Feb 26 Copyright © Cengage Learning. All rights reserved 28 Return to TOC