# Chapter 14. CHEMICAL EQUILIBRIUM

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 Chapter 14. CHEMICAL EQUILIBRIUM 14.1 THE CONCEPT OF EQUILIBRIUM AND THE EQUILIBRIUM CONSTANT Many chemical reactions do not go to completion but instead attain a state of chemical equilibrium. Chemical equilibrium: A state in which the rates of the forward and reverse reactions are equal and the concentrations of the reactants and products remain constant. Equilibrium is a dynamic process the conversions of reactants to products and products to reactants are still going on, although there is no net change in the number of reactant and product molecules. For the reaction: N O 4 (g) NO (g) concentration N O 4 NO Rate Forward rate Reverse rate time The Equilibrium Constant For a reaction: aa + bb cc + dd c d [ C] [ D] equilibrium constant: K c = a b [ A] [ B] The equilibrium constant, K c, is the ratio of the equilibrium concentrations of products over the equilibrium concentrations of reactants each raised to the power of their stoichiometric coefficients. Example. Write the equilibrium constant, K c, for N O 4 (g) NO (g) time Law of mass action - The value of the equilibrium constant expression, K c, is constant for a given reaction at equilibrium and at a constant temperature. The equilibrium concentrations of reactants and products may vary, but the value for K c remains the same. Other Characteristics of K c 1) Equilibrium can be approached from either direction. ) K c does not depend on the initial concentrations of reactants and products. 3) K c does depend on temperature. Magnitude of K c If the K c value is large (K c >> 1), the equilibrium lies to the right and the reaction mixture contains mostly products. If the K c value is small (K c <<1), the equilibrium lies to the left and the reaction mixture contains mostly reactants. If the K c value is close to 1 (0.10 < K c < 10), the mixture contains appreciable amounts of both reactants and products. Chapter 14 Equilibrium Notes page 1 of 6

2 14. WRITING EQUILIBRIUM CONSTANT EXPRESSIONS Calculating Equilibrium Constants, K c K c values are listed without units don't include units when calculating K c. If equilibrium concentrations are known, simply substitute the concentrations into the equilibrium constant expression: Example. For the reaction, CO + 3H CH 4 + H O, calculate K c from the following equilibrium concentrations: [CO] = M; [H ] = M; [CH 4 ] = M; [H O] = M. Homogeneous equilibria: reactants and products exist in a single phase. For the gas phase reaction: N O 4 (g) NO (g) The equilibrium constant with the concentrations of reactants and products expressed in terms of molarity, K c, is: [NO ] K c = [N O ] 4 Gas Phase Expressions can also be expressed by K p The K p expression is written using equilibrium partial pressures of reactants & products. For the reaction given above, the K p expression is: K p = P P NO NO4 K p is related to K c Since pressure and molarity are related by the Ideal Gas Law, the following equation relates K p and K c : K p = K c (RT) n L atm where R = ; T = temperature in Kelvin K mol n = moles of gaseous products moles of gaseous reactants Note that K c = K p when the number of gas molecules are the same on both sides. Example. Does K c = K p for (a) H (g) + F (g) HF(g)? (b) SO (g) + O (g) SO 3 (g)? Example. For the reaction, SO (g) + O (g) SO 3 (g) (a) write the equilibrium constant expression, K p. (b) What is the value for K p if K c =.8x10 at 1000 K? Heterogeneous Equilibria and Solvents in Homogeneous Equilibria Heterogeneous equilibria: reactants and products are present in more than one phase. Chapter 14 Equilibrium Notes page of 6

3 pure solids and liquids: concentrations of pure solids and liquids are fixed by their density and molar mass (both constants) and do not vary with the amount. [] = M = Density Molar Mass mol g 10 3 ml M = = L ml 1L Thus, the concentrations of solids and liquids are incorporated in the K c value; they are not part of the variable K c expression: Example. Write the K c expression for CaCO 3 (s) CaO(s) + CO (g) mol g Omit concentration terms for solids and liquids from K c and K p expressions; only include terms for gases (g) and aqueous substances (aq). Example. Write the K c expression for the following reaction: 3Cu(s) + NO 3 - (aq) + 8H + (aq) 3Cu + (aq) + NO(g) + 4H O(l) Modifying Equilibrium Constant Expressions: A. Changing stoichiometric coefficients: 1) SO + O SO 3 K 1 = ) SO + 1 O SO 3 K = If we multiply an equation by a factor, we must raise its K to that power to get the new K. B. Reversing the reaction: 3) SO 3 SO + O K 3 = K is the reciprocal of the K value for the reverse reaction. C. Adding Equations for Multiple Equilibrium Reactions: 1. A + B C K 1 =. A + D B K = 3. A + B + D C K 3 = When we add equations to get a new equation, the new K is the product of the other K s. Example. H (g) + O (g) H O(g) K c = 1.7x10 7 N (g) + 3H (g) NH 3 (g) K c = 1.5x10 Calculate the value of K c for 4NH 3 (g) + 3O (g) N (g) + 6H O(g) Chapter 14 Equilibrium Notes page 3 of 6

4 14.3 THE RELATIONSHIP BETWEEN CHEMICAL KINETICS AND CHEMICAL EQUILIBRIUM For the reaction N O 4 (g) NO (g) Rate of forward reaction = Rate of reverse reaction k f [N O 4 ] = k r [NO ] [ NO ] k f Rearrange: = = K c [ N O4 ] kr Thus, the equilibrium constant is simply the ratio of the forward and reverse rate constants which are both constant values at a given temperature WHAT DOES THE EQUILIBRIUM CONSTANT TELL US? Predicting the Direction of Reaction The reaction quotient, Q, is the resulting value when we substitute reactant and product concentrations into the equilibrium expression. 1. If Q > K, the reaction will go to the left. The ratio of products over reactants is too large & the reaction will move toward equilibrium by forming more reactants.. If Q < K, the reaction will go to the right. The ratio of products over reactants is too small & the reaction will move toward equilibrium by forming more products. 3. If Q = K, the reaction mixture is already at equilibrium, so no shift occurs. Example. For the reaction, B A, K c =. Suppose 3.0 moles of A and 3.0 moles of B are introduced into a.00 L flask. (a) In which direction will the reaction proceed to attain equilibrium? (b) Will the concentration of B increase, decrease or remain the same as the system moves towards equilibrium? Calculating Equilibrium Concentrations Use ICE Tables To Solve Equilibrium Problems For K c Or Equilibrium Amounts: 1. I = initial concentration: Initial concentration of reactants are usually given; initial [Product]'s are assumed to be 0 unless otherwise specified.. C = change in concentration: Assign change as the variable x; use the stoichiometry of the reaction to assign changes for all species. 3. E = equilibrium concentration: E = I + C Note, values in ICE tables can be in terms of moles or Molarity (or atm for K p ), but values used in the K c expression must be in terms of Molarity (or atm for K p ). Chapter 14 Equilibrium Notes page 4 of 6

5 Example. When 0.50 mol SO and 0.00 mol O are placed in a 10.0 L vessel at 1000 K, the equilibrium mixture was found to contain 0.16 mol SO 3. Calculate K c for this reaction: SO (g) + O (g) SO 3 (g) Method to find equilibrium concentrations 1) Set up the ICE table. ) Set up the K c expression; substitute equilibrium concentrations from the ICE table into K c. 3) Solve for x; plug the solution for x back into the equilibrium concentration expressions. Perfect square problem to solve for x Take the square root of both sides when the math expression is a perfect square. Example. At 430 C, K p = 54.3 for the following reaction: H (g) + I (g) HI(g) A mixture of H at a pressure of atm and I at a pressure of atm is placed in a container at 430 C. Calculate the equilibrium partial pressures of HI, H and I. Quadratic Formula Example For this reaction, H (g) + F (g) HF(g), K c = 1.15x10 at a certain temperature. Suppose moles of H and moles of F are placed in a L container. What are the equilibrium concentrations of H, F and HF? Chapter 14 Equilibrium Notes page 5 of 6

6 14.5 FACTORS THAT AFFECT CHEMICAL EQUILIBRIUM Le Chatelier's Principle: If a system at equilibrium is disturbed by an external stress, the system adjusts to partially offset the stress as the system attains a new equilibrium position. Changes in Concentration Adding a reactant or product, the equilibria shifts away from the increase in order to consume part of the added substance. Removing a reactant or product, the equilibria shifts toward the decrease to replace part of the removed species. E.g. For H + I HI, does the equilibria shift left or right if we: a) add H? b) remove I? a) b) Changes in Volume and Pressure Because the pressure of gases is related directly to the concentration by P = n/v, changing the pressure by increasing/decreasing the volume of a container will disturb an equilibrium system. If P increases (V decreases), the system shifts to the side with a smaller number of gas molecules (this effectively reestablishes equilibrium by decreasing the pressure). If P decreases (V increases), the system shifts to the side with a greater number of gas molecules. Example. For N (g) + 3H (g) NH 3 (g), does the equilibrium shift left or right if the pressure is increased? Changes in Temperature Heat can be considered a reactant in an endothermic rxn and a product in an exothermic rxn. Endothermic ( H > 0) R + Heat Products Exothermic ( H < 0) R Products + Heat Recall that both K c and the position of the equilibrium system will vary with temperature: K c is larger when the reaction shifts right. This occurs if T is increased for an Endothermic Reaction or T is decreased for an Exothermic reaction. K c is smaller when the reaction shifts left. This occurs if T is decreased for an Endothermic Reaction or T is increased for an Exothermic reaction. Example. If the temperature is decreased for the reaction: CO CO + O, H = 566 kj. a) Will the equilibrium shift left or right? b) Does K c become larger or smaller? Effect of a Catalyst Catalysts lower E a for the reaction, so a catalyst decreases the amount of time taken to reach equilibrium for both the forward and reverse reactions. The catalyst does not affect the equilibrium concentrations of reactants and products in the equilibrium mixture; thus, the K c value does not change. Choosing Optimum Conditions Le Chatelier s principle can be used to select optimum conditions to form a substance. e.g. To form more NH 3, predict the optimum conditions for temperature and pressure. N (g) + 3H (g) NH 3 (g) H = kj Chapter 14 Equilibrium Notes page 6 of 6

### CHAPTER 14 (MOORE) CHEMICAL EQUILIBRIUM

CHAPTER 14 (MOORE) CHEMICAL EQUILIBRIUM This chapter deals with chemical equilibrium, or how far chemical reactions proceed. Some reactions convert reactants to products with near 100% efficiency but others

### Sample Exercise 15.1 Writing Equilibrium-Constant Expressions

Sample Exercise 15.1 Writing Equilibrium-Constant Expressions Write the equilibrium expression for K c for the following reactions: Solution Analyze: We are given three equations and are asked to write

### Principles of Reactivity: Chemical Equilibria

Principles of Reactivity: Chemical Equilibria This chapter addresses the principle of equilibrium equilibrium What can you do to reestablish equilibrium? non-equilibrium Whose principle supports this?

### CHEMICAL EQUILIBRIUM

Chemistry 10 Chapter 14 CHEMICAL EQUILIBRIUM Reactions that can go in both directions are called reversible reactions. These reactions seem to stop before they go to completion. When the rate of the forward

### A k 1. At equilibrium there is no net change in [A] or [B], namely d[a] dt

Chapter 15: Chemical Equilibrium Key topics: Equilibrium Constant Calculating Equilibrium Concentrations The Concept of Equilibrium Consider the reaction A k 1 k 1 B At equilibrium there is no net change

### Chapter 14 Chemical Equilibrium

Chapter 14 Chemical Equilibrium Forward reaction H 2 (g) + I 2 (g) 2HI(g) Reverse reaction 2HI(g) H 2 (g) + I 2 (g) At equilibrium H 2 (g) + I 2 (g) 2HI(g) Chemical equilibrium is reached when reactants

### K c = [C]c [D] d [A] a [B] b. k f [NO 2 ] = k r [N 2 O 4 ] = K eq = The Concept of Equilibrium. Chapter 15 Chemical Equilibrium

Chapter 15 Chemical Equilibrium Learning goals and key skills: Understand what is meant by chemical equilibrium and how it relates to reaction rates Write the equilibrium-constant expression for any reaction

### Chapter 13 - Chemical Equilibrium

Chapter 1 - Chemical Equilibrium Intro A. Chemical Equilibrium 1. The state where the concentrations of all reactants and products remain constant with time. All reactions carried out in a closed vessel

### Gas Phase Equilibrium

Gas Phase Equilibrium Chemical Equilibrium Equilibrium Constant K eq Equilibrium constant expression Relationship between K p and K c Heterogeneous Equilibria Meaning of K eq Calculations of K c Solving

### Equilibrium Notes Ch 14:

Equilibrium Notes Ch 14: Homework: E q u i l i b r i u m P a g e 1 Read Chapter 14 Work out sample/practice exercises in the sections, Bonus Chapter 14: 23, 27, 29, 31, 39, 41, 45, 51, 57, 63, 77, 83,

### Chemical Equilibrium

Chemical Equilibrium Chapter 14 1 Equilibrium is a state in which there are no observable changes as time goes by. Chemical equilibrium is achieved when: the rates of the forward and reverse reactions

### Chapter 13. Chemical Equilibrium

Chapter 13 Chemical Equilibrium Section 13.1 The Equilibrium Condition Section 13.1 The Equilibrium Condition Section 13.1 The Equilibrium Condition Section 13.1 The Equilibrium Condition Section 13.1

### Chemical Equilibrium

Chapter 13 Chemical Equilibrium Equilibrium Physical Equilibrium refers to the equilibrium between two or more states of matter (solid, liquid and gas) A great example of physical equilibrium is shown

### Chemical Equilibrium - Chapter 14

Chemical Equilibrium - Chapter 14 1. Dynamic Equilibrium a A + b B c C + d D At Equilibrium: Reaction is proceeding in both directions at the same rate. There is no net change in concentrations of reactants

### Chapter 13. Chemical Equilibrium

Chapter 13 Chemical Equilibrium Chapter 13 Preview Chemical Equilibrium The Equilibrium condition and constant Chemical equilibrium, reactions, constant expression Equilibrium involving Pressure Chemical

### AP* Chemistry CHEMICAL EQUILIBRIA: GENERAL CONCEPTS

AP* Chemistry CHEMICAL EQUILIBRIA: GENERAL CONCEPTS THE NATURE OF THE EQUILIBRIUM STATE: Equilibrium is the state where the rate of the forward reaction is equal to the rate of the reverse reaction. At

### Chapter 15 Chemical Equilibrium

Chapter 15 Chemical Equilibrium Chemical reactions can reach a state of dynamic equilibrium. Similar to the equilibrium states reached in evaporation of a liquid in a closed container or the dissolution

### Chemical Equilibrium. Rate Forward Reaction = Rate Reverse Reaction. Chapter 14. Hill, Petrucci, McCreary & Perry 4 th. Ed.

Chapter 14 Chemical Equilibrium Hill, Petrucci, McCreary & Perry 4 th Ed. Chemical Equilibrium Many Reactions seem to STOP before all the reactants are used up. The Concentrations of Reactants and Products

### Chapter 13 Chemical Equilibrium. Equilibrium is Dynamic. The Equilibrium Constant. Equilibrium and Catalysts. Characteristics of Chemical Equilibrium

Characteristics of Chemical Equilibrium John W. Moore Conrad L. Stanitski Peter C. Jurs http://academic.cengage.com/chemistry/moore Chapter 13 Chemical Equilibrium Many reactions fail to go to completion.

### Chemical Equilibrium-A Dynamic Equilibrium

Chemical Equilibrium-A Dynamic Equilibrium Page 1 When compounds react, they eventually form a mixture of products and (unreacted) reactants, in a dynamic equilibrium Much like water in a U-shape tube,

EQUILIBRIUM Academic Success Center Definition Equilibrium is a state where the concentrations of the reactants and products no longer change with time. This doesn t mean there is no movement between the

### Answers: Given: No. [COCl 2 ] = K c [CO][Cl 2 ], but there are many possible values for [CO]=[Cl 2 ]

Chemical Equilibrium What are the concentrations of reactants and products at equilibrium? How do changes in pressure, volume, temperature, concentration and the use of catalysts affect the equilibrium

### Chapter 15: Chemical Equilibrium: How Much Product Does a Reaction Really Make?

Chapter 15: Chemical Equilibrium: How Much Product Does a Reaction Really Make? End-of-Chapter Problems: 15.1-15.10, 15.13-15.14, 15.17-15.99, 15.102-15.104 Example: Ice melting is a dynamic process: H

### CHEM 1332 CHAPTER 14

CHEM 1332 CHAPTER 14 1. Which is a proper description of chemical equilibrium? The frequencies of reactant and of product collisions are identical. The concentrations of products and reactants are identical.

### Chemistry 4th Edition McMurry/Fay

13 Ch a pt e r Chemical Equilibrium Chemistry 4th Edition McMurry/Fay Dr. Paul Charlesworth Michigan Technological University The Equilibrium State 01 Chemical Equilibrium: A state achieved when the rates

### Equilibrium. Equilibrium 1. Examples of Different Equilibria. K p H 2 + N 2 NH 3 K a HC 2 H 3 O 2 H C 2 H 3 O 2 K sp SrCrO 4 Sr CrO 4

Equilibrium 1 Equilibrium Examples of Different Equilibria K p H 2 + N 2 NH 3 K a HC 2 H 3 O 2 H + - + C 2 H 3 O 2 K sp SrCrO 4 Sr 2+ 2- + CrO 4 Equilibrium deals with: What is the balance between products

### Ch14 Chemical Equilibrium. Modified by Dr. Cheng-Yu Lai

Ch14 Chemical Equilibrium Modified by Dr. Cheng-Yu Lai CHEMICAL EQUILIBRIUM Chemical Equilibrium: Chemical Equilibrium When the rate of the forward reaction equals the rate of the reverse reaction and

### CH 223 Chapter Thirteen Concept Guide

CH 223 Chapter Thirteen Concept Guide 1. Writing Equilibrium Constant Expressions Write the equilibrium constant (K c ) expressions for each of the following reactions: (a) Cu(OH) 2 (s) (b) Cu(NH 3 ) 4

### CHEMICAL EQUILIBRIUM (ICE METHOD)

CHEMICAL EQUILIBRIUM (ICE METHOD) Introduction Chemical equilibrium occurs when opposing reactions are proceeding at equal rates. The rate at which the products are formed from the reactants equals the

### Chemical Equilibrium. Chapter 13

Chemical Equilibrium Chapter 13 Chemical Equilibrium When neither the products nor the reactant concentrations change any more with time. Chemical Equilibrium When the forward rate of reaction is equal

### Equilibrium. Ron Robertson

Equilibrium Ron Robertson Basic Ideas A. Extent of Reaction Many reactions do not go to completion. Those that do not are reversible with a forward reaction and reverse reaction. To be really correct we

### Guide to Chapter 13. Chemical Equilibrium

Guide to Chapter 13. Chemical Equilibrium We will spend five lecture days on this chapter. During the first class meeting we will focus on how kinetics makes a segue into equilibrium. We will learn how

### EQUILIBRIUM. Consider the reversible system initially consisting of reactants only.

EQUILIBRIUM When non reversible chemical reactions proceed to completion, the concentration of the reactants gradually decrease, until there is NO limiting reactant remaining. Most chemical reactions,

### Chemical Equilibria & the Application of Le Châtelier s Principle to General Equilibria. Example of Equilibrium. !A(g) + "B(g)!

Chemical Equilibria & the Application of Le Châtelier s Principle to General Equilibria CHEM 102H T. Hughbanks Example of Equilibrium N 2 + 3H 2! 2 NH 3 Reactions can occur, in principle, in either direction.

### IN CHAPTER 13, we examined how fast a chemical reaction occurs. In this chapter we. Chemical Equilibrium

14 Chemical Equilibrium Every system in chemical equilibrium, under the influence of a change of any one of the factors of equilibrium, undergoes a transformation... [that produces a change]... in the

### Chapter 20. Thermodynamics p. 811 842. Spontaneity. What have we learned about spontaneity during this course?

Chapter 20 p. 811 842 Spontaneous process: Ex. Nonspontaneous process: Ex. Spontaneity What have we learned about spontaneity during this course? 1) Q vs. K? 2) So.. Spontaneous process occurs when a system

### We will be looking at: A. Judging the extent of a reaction B. Predicting the direction of a reaction C. Calculating equilibrium concentrations

13.5 Using the Equilibrium Constant We will be looking at: A. Judging the extent of a reaction B. Predicting the direction of a reaction C. Calculating equilibrium concentrations A. Judging the extent

### Name AP Chemistry / / Chapter 13 Collected AP Exam Free Response Questions 1980 2010 Answers

Name AP Chemistry / / Chapter 13 Collected AP Exam Free Response Questions 1980 2010 Answers 1980 - #6 NH 4 Cl(s) NH 3 (g) + HCl(g) ΔH = +42.1 kilocalories Suppose the substances in the reaction above

### Test Review # 9. Chemistry R: Form TR9.13A

Chemistry R: Form TR9.13A TEST 9 REVIEW Name Date Period Test Review # 9 Collision theory. In order for a reaction to occur, particles of the reactant must collide. Not all collisions cause reactions.

### Equilibrium Lecture #1. Schweitzer

Equilibrium Lecture #1 Schweitzer What is equilibrium? Remember Equilibrium process between to competing reactions. At equilibrium the forward process is equal to the reverse process. *** It appears that

### CHAPTER 14 CHEMICAL EQUILIBRIUM

CHATER 14 CHEMICAL EQUILIBRIUM roblem Categories Biological: 14.98. Conceptual: 14.1, 14., 14.9, 14.5, 14.54, 14.55, 14.56, 14.57, 14.58, 14.59, 14.60, 14.61, 14.6, 14.66, 14.67, 14.68, 14.69, 14.81, 14.91,

### Chemistry 212 EXAM 1 January 27, 2004

1 Chemistry 212 EXAM 1 January 27, 2004 _100 (of 100) KEY Name Part 1: Multiple Choice. (1 point each, circle only one answer, 1. Consider the following rate law: Rate = k[a] n [B] m How are the exponents

### Ch 3. Rate Laws and Stoichiometry

Ch 3. Rate Laws and Stoichiometry How do we obtain r A = f(x)? We do this in two steps 1. Rate Law Find the rate as a function of concentration, r A = k fn (C A, C B ). Stoichiometry Find the concentration

### Equilibrium Practice Problems

Equilibrium Practice Problems 1. Write the equilibrium expression for each of the following reactions: N 2 (g) + 3 H 2 (g) 2 NH 3 (g) K = [NH 3 ] 2 [N 2 ] [H 2 ] 3 I 2 (s) + Cl 2 (g) 2 ICl (g) K = [ICl]

### MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

A.P. Chemistry Practice Test - Ch. 13: Equilibrium Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) At equilibrium,. A) the rates of the forward

### Worked solutions to student book questions Chapter 16 Controlling the yield of reactions

E1. Write an equation to show the equilibrium that exists between NaI(s) and Na + (aq) and I (aq). AE1. NaI(s) Na + (aq) + I (aq) E. a Sketch a graph of the change in the radioactivity of the solution

### CHEM1612 2014-N-2 November 2014

CHEM1612 2014-N-2 November 2014 Explain the following terms or concepts. Le Châtelier s principle 1 Used to predict the effect of a change in the conditions on a reaction at equilibrium, this principle

### Equilibrium, Acids and Bases Unit Summary:

Equilibrium, Acids and Bases Unit Summary: Prerequisite Skills and Knowledge Understand concepts of concentration, solubility, saturation point, pressure, density, viscosity, flow rate, and temperature

Thermochemistry Reading: Chapter 5 (omit 5.8) As you read ask yourself What is meant by the terms system and surroundings? How are they related to each other? How does energy get transferred between them?

Chapter 18 Homework Answers 18.22. 18.24. 18.26. a. Since G RT lnk, as long as the temperature remains constant, the value of G also remains constant. b. In this case, G G + RT lnq. Since the reaction

### Chemical Equilibrium. Chapter 17: Keeping the chemical themes straight. Chapter 17 Homework Problems. N2O4 (g) 2NO2 (g)

Chapter 17: Chemical Equilibrium Equilibrium: The Extent of Chemical Reactions 17.1 The Dynamic Nature of the Equilibrium State 17. The Reaction Quotient and the Equilibrium Constant 17.3 Expressing Equilibria

### SECTION 14 CHEMICAL EQUILIBRIUM

1-1 SECTION 1 CHEMICAL EQUILIBRIUM Many chemical reactions do not go to completion. That is to say when the reactants are mixed and the chemical reaction proceeds it only goes to a certain extent, and

### Consider: N 2 (g) + 3H 2 (g) 2NH 3 (g) G = -32.90 kj/mol. conc. time

5.111 Lecture Summary #19 CHEMICAL EQUILIBRIUM (Chapter 9 Section 9.0-9.9) Topics Nature of Chemical Equilibrium Meaning of K Relationship between Equilibrium Expressions External Effects on K 19.1 Chemical

### The first law: transformation of energy into heat and work. Chemical reactions can be used to provide heat and for doing work.

The first law: transformation of energy into heat and work Chemical reactions can be used to provide heat and for doing work. Compare fuel value of different compounds. What drives these reactions to proceed

### Chemistry B11 Chapter 4 Chemical reactions

Chemistry B11 Chapter 4 Chemical reactions Chemical reactions are classified into five groups: A + B AB Synthesis reactions (Combination) H + O H O AB A + B Decomposition reactions (Analysis) NaCl Na +Cl

### Optional Homework 6 do not turn in!!

Name: Date: Optional Homework 6 do not turn in!! 1.) What is the first thing you must do to a reaction in order to write an accurate equilibrium (K) expression? Give a real example of a K expression: You

### 7. 1.00 atm = 760 torr = 760 mm Hg = 101.325 kpa = 14.70 psi. = 0.446 atm. = 0.993 atm. = 107 kpa 760 torr 1 atm 760 mm Hg = 790.

CHATER 3. The atmosphere is a homogeneous mixture (a solution) of gases.. Solids and liquids have essentially fixed volumes and are not able to be compressed easily. have volumes that depend on their conditions,

### Standard Free Energies of Formation at 298 K. Average Bond Dissociation Energies at 298 K

1 Thermodynamics There always seems to be at least one free response question that involves thermodynamics. These types of question also show up in the multiple choice questions. G, S, and H. Know what

### 2. Write a balanced chemical equation which corresponds to the following equilibrium constant expression. 1/2 3/ 2

Practice Problems for Chem. 1B Exam 1 F2011 These represent the concepts covered for exam 1. There may be some additional net ionic equations from chem. 1A. This is not the exact exam! Sections 16.1-16.3

### Name AP CHEM / / Collected AP Exam Essay Answers for Chapter 16

Name AP CHEM / / Collected AP Exam Essay Answers for Chapter 16 1980 - #7 (a) State the physical significance of entropy. Entropy (S) is a measure of randomness or disorder in a system. (b) From each of

### V. POLYPROTIC ACID IONIZATION. NOTICE: K a1 > K a2 > K a3 EQUILIBRIUM PART 2. A. Polyprotic acids are acids with two or more acidic hydrogens.

EQUILIBRIUM PART 2 V. POLYPROTIC ACID IONIZATION A. Polyprotic acids are acids with two or more acidic hydrogens. monoprotic: HC 2 H 3 O 2, HCN, HNO 2, HNO 3 diprotic: H 2 SO 4, H 2 SO 3, H 2 S triprotic:

### CHAPTER 17 EQUILIBRIUM: THE EXTENT OF CHEMICAL REACTIONS

CHATER 17 EQUILIBRIUM: THE EXTENT OF CHEMICAL REACTIONS END OF CHATER ROBLEMS 17.1 If the rate of the forward reaction exceeds the rate of reverse reaction, products are formed faster than they are consumed.

### CHAPTER 17 EQUILIBRIUM: THE EXTENT OF CHEMICAL REACTIONS

CHATER 17 EQUILIBRIUM: THE EXTENT OF CHEMICAL REACTIONS 17.1 If the rate of the forward reaction exceeds the rate of reverse reaction, products are formed faster than they are consumed. The change in reaction

### CHEM 102 CLASS NOTES Prof. Upali Siriwardane, Chemistry Program, Louisiana Tech University, Ruston, LA 71272 CHAPTER 14, Chemical Equilibrium Chapter

CHEM 10 CLASS NOTES Prof. Upali Siriwardane, Chemistry Program, Louisiana Tech University, Ruston, LA 717 CHAPTER 14, Chemical Equilibrium Chapter 14. Chemical Equilibrium 14.1 Characteristics of Chemical

### THERMOCHEMISTRY & DEFINITIONS

THERMOCHEMISTRY & DEFINITIONS Thermochemistry is the study of the study of relationships between chemistry and energy. All chemical changes and many physical changes involve exchange of energy with the

### Ca 3 N 2 (s) + 6H 2 O(l) H 2NH 3 (g) + 3Ca(OH) 2 (s) mole ratio 1 : 6 : 2 : 3 molar mass (g/mole)

1. STOICHIOMETRY INVOLVING ONLY PURE SUBSTANCES For all chemical reactions, the balanced chemical equation gives the mole ratios of reactants and products. If we are dealing with pure chemicals, the molar

### Three Stooges in Chemical Reactions

Three Stooges in Chemical Reactions Introduction: Amina Khalifa El-Ashmawy, Ph.D. Gezahegn Chaka, Ph.D. Collin College Department of Chemistry Imagine an old black and white television comedy like the

### AP Chemistry 2004 Scoring Guidelines Form B

AP Chemistry 2004 Scoring Guidelines Form B The materials included in these files are intended for noncommercial use by AP teachers for course and exam preparation; permission for any other use must be

### AP CHEMISTRY 2009 SCORING GUIDELINES (Form B)

AP CHEMISTRY 2009 SCORING GUIDELINES (Form B) Question 3 (10 points) 2 H 2 O 2 (aq) 2 H 2 O(l) + O 2 (g) The mass of an aqueous solution of H 2 O 2 is 6.951 g. The H 2 O 2 in the solution decomposes completely

### AP* Chemistry THERMOCHEMISTRY

AP* Chemistry THERMOCHEMISTRY Terms for you to learn that will make this unit understandable: Energy (E) the ability to do work or produce heat ; the sum of all potential and kinetic energy in a system

### b. Calculate the value of the equilibrium constant at 127ºC for the reaction 2NH 3 (g) N 2 (g) + 3H 2 (g)

1. Write the equilibrium expression for the following reaction: 4NH 3 (g) + 7O 2 (g) 4NO 2 (g) + 6H 2 O(g) 2. The following equilibrium concentrations were observed for this reaction at 127ºC: N 2 (g)

### Moles and Chemical Reactions. Moles and Chemical Reactions. Molar mass = 2 x 12.011 + 6 x 1.008 + 1 x15.999 = 46.069 g/mol

We have used the mole concept to calculate mass relationships in chemical formulas Molar mass of ethanol (C 2 H 5 OH)? Molar mass = 2 x 12.011 + 6 x 1.008 + 1 x15.999 = 46.069 g/mol Mass percentage of

### AP Chemistry Unit 7- Homework Problems Equilibrium and K sp

AP Chemistry Unit 7- Homework Problems Equilibrium and K sp Nature of the Equilibrium State 1. Draw on this graph where equilibrium has been reached. [X] equilibrium time 2. What are three qualities of

### Thermodynamics- Chapter 19 Schedule and Notes

Thermodynamics- Chapter 19 Schedule and Notes Date Topics Video cast DUE Assignment during class time One Review of thermodynamics 1_thermo_review AND Review of thermo Wksheet 2.1ch19_intro Optional: 1sc_thermo

### Introductory Chemistry, 3 rd Edition Nivaldo Tro. Roy Kennedy Massachusetts Bay Community College Wellesley Hills, Maqqwertd ygoijpk[l

Introductory Chemistry, 3 rd Edition Nivaldo Tro Quantities in Car an octane and oxygen molecules and carbon dioxide and water Chemical Reactions Roy Kennedy Massachusetts Bay Community College Wellesley

### Chemical Equilibrium. Part A Unit-based exercise. Topic 11. Unit 39 An introduction to chemical equilibrium. Fill in the blanks.

Topic 11 hemical Equilibrium Part A Unit-based exercise Unit 39 An introduction to chemical equilibrium Fill in the blanks 1 hemical reaction that take place in one direction only are known as irreversible

### AP Practice Questions

1) AP Practice Questions The tables above contain information for determining thermodynamic properties of the reaction below. C 2 H 5 Cl(g) + Cl 2 (g) C 2 H 4 Cl 2 (g) + HCl(g) (a) Calculate ΔH for

### Problem Solving. Stoichiometry of Gases

Skills Worksheet Problem Solving Stoichiometry of Gases Now that you have worked with relationships among moles, mass, and volumes of gases, you can easily put these to work in stoichiometry calculations.

### CHM111 Lab Enthalpy of Hydration of Sodium Acetate Grading Rubric

Name Team Name CHM111 Lab Enthalpy of Hydration of Sodium Acetate Grading Rubric Criteria Points possible Points earned Lab Performance Printed lab handout and rubric was brought to lab 3 Safety and proper

### 1. solid, vapor, critical point correct. 2. solid, liquid, critical point. 3. liquid, vapor, critical point. 4. solid, liquid, triple point

mcdonald (pam78654) HW 7B: Equilibria laude (89560) 1 This print-out should have 18 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0

### Thermochemical equations allow stoichiometric calculations.

CHEM 1105 THERMOCHEMISTRY 1. Change in Enthalpy ( H) Heat is evolved or absorbed in all chemical reactions. Exothermic reaction: heat evolved - heat flows from reaction mixture to surroundings; products

### CHEMICAL EQUILIBRIUM Chapter 13

Page 1 1 hemical Equilibrium EMIAL EQUILIBRIUM hapter 1 The state where the concentrations of all reactants and products remain constant with time. On the molecular level, there is frantic activity. Equilibrium

### AP Chemistry 2007 Scoring Guidelines Form B

AP Chemistry 2007 Scoring Guidelines Form B The College Board: Connecting Students to College Success The College Board is a not-for-profit membership association whose mission is to connect students to

### CHEM 36 General Chemistry EXAM #1 February 13, 2002

CHEM 36 General Chemistry EXAM #1 February 13, 2002 Name: Serkey, Anne INSTRUCTIONS: Read through the entire exam before you begin. Answer all of the questions. For questions involving calculations, show

### CHEMISTRY. Matter and Change. Section 13.1 Section 13.2 Section 13.3. The Gas Laws The Ideal Gas Law Gas Stoichiometry

CHEMISTRY Matter and Change 13 Table Of Contents Chapter 13: Gases Section 13.1 Section 13.2 Section 13.3 The Gas Laws The Ideal Gas Law Gas Stoichiometry State the relationships among pressure, temperature,

### Gas particles move in straight line paths. As they collide, they create a force, pressure.

#28 notes Unit 4: Gases Ch. Gases I. Pressure and Manometers Gas particles move in straight line paths. As they collide, they create a force, pressure. Pressure = Force / Area Standard Atmospheric Pressure

### INTI COLLEGE MALAYSIA A? LEVEL PROGRAMME CHM 111: CHEMISTRY MOCK EXAMINATION: DECEMBER 2000 SESSION. 37 74 20 40 60 80 m/e

CHM111(M)/Page 1 of 5 INTI COLLEGE MALAYSIA A? LEVEL PROGRAMME CHM 111: CHEMISTRY MOCK EXAMINATION: DECEMBER 2000 SESSION SECTION A Answer ALL EIGHT questions. (52 marks) 1. The following is the mass spectrum

### Mr. Bracken. Multiple Choice Review: Thermochemistry

Mr. Bracken AP Chemistry Name Period Multiple Choice Review: Thermochemistry 1. If this has a negative value for a process, then the process occurs spontaneously. 2. This is a measure of how the disorder

### Chapter 3: Stoichiometry

Chapter 3: Stoichiometry Key Skills: Balance chemical equations Predict the products of simple combination, decomposition, and combustion reactions. Calculate formula weights Convert grams to moles and

### 3. Of energy, work, enthalpy, and heat, how many are state functions? a) 0 b) 1 c) 2 d) 3 e) 4 ANS: c) 2 PAGE: 6.1, 6.2

1. A gas absorbs 0.0 J of heat and then performs 15.2 J of work. The change in internal energy of the gas is a) 24.8 J b) 14.8 J c) 55.2 J d) 15.2 J ANS: d) 15.2 J PAGE: 6.1 2. Calculate the work for the

### Equilibria Involving Acids & Bases

Week 9 Equilibria Involving Acids & Bases Acidic and basic solutions Self-ionisation of water Through reaction with itself: The concentration of water in aqueous solutions is virtually constant at about

### Chapter 4 An Introduction to Chemical Reactions. An Introduction to Chemistry by Mark Bishop

Chapter 4 An Introduction to Chemical Reactions An Introduction to Chemistry by Mark Bishop Chapter Map Chemical Reaction A chemical change or chemical reaction is a process in which one or more pure substances

### Chapter 3. Chemical Reactions and Reaction Stoichiometry. Lecture Presentation. James F. Kirby Quinnipiac University Hamden, CT

Lecture Presentation Chapter 3 Chemical Reactions and Reaction James F. Kirby Quinnipiac University Hamden, CT The study of the mass relationships in chemistry Based on the Law of Conservation of Mass

### Ch 8.5 Solution Concentration Units % (m/m or w/w) = mass of solute x 100 total mass of solution mass of solution = mass solute + mass solvent

1 Ch 8.5 Solution Concentration Units % (m/m or w/w) = mass of solute x 100 total mass of solution mass of solution = mass solute + mass solvent % (v/v) = volume of solute x 100 volume of solution filled

### Chemistry 106 Fall 2007 Exam 3 1. Which one of the following salts will form a neutral solution on dissolving in water?

1. Which one of the following salts will form a neutral solution on dissolving in water? A. NaCN B. NH 4 NO 3 C. NaCl D. KNO 2 E. FeCl 3 2. Which one of the following is a buffer solution? A. 0.10 M KCN

### ENERGY. Thermochemistry. Heat. Temperature & Heat. Thermometers & Temperature. Temperature & Heat. Energy is the capacity to do work.

ENERGY Thermochemistry Energy is the capacity to do work. Chapter 6 Kinetic Energy thermal, mechanical, electrical, sound Potential Energy chemical, gravitational, electrostatic Heat Heat, or thermal energy,

### Boyles Law. At constant temperature the volume occupied by a fixed amount of gas is inversely proportional to the pressure on the gas 1 P = P

Boyles Law At constant temperature the volume occupied by a fixed amount of gas is inversely proportional to the pressure on the gas 1 or k 1 Boyles Law Example ressure olume Initial 2.00 atm 100 cm 3