Chapter 9. Chemical Reactions Chapter 9 Table Of Contents
5/8/2017Chapter 9Chapter 9. Chemical ReactionsTable of ContentsIntroduction to Inorganic ChemistryInstructor Dr. Upali Siriwardane (Ph.D. Ohio State)E-mail: upali@latech.eduOffice: 311 Carson Taylor Hall ; Phone: 318-257-4941;Office Hours: MWF 8:00-9:00 and 11:00-12:00;TR 10:00-12:00Contact me trough phone or e-mail if you have questionsOnline Tests on Following daysMarch 24, 2017: Test 1 (Chapters 1-3)April 10, 2017 :Test 2 (Chapters 4-5)May 1, 2017: Test 3 (Chapters 6,7 &8)May 12, 2017 : Test 4 (Chapters 9, 10 &11)May 15, 2017: Make Up Exam: Chapters 1-11).9.19.29.39.49.59.69.79.89.9Types of Chemical ReactionsRedox and Nonredox Chemical ReactionsTerminology Associated with Redox ProcessesCollision Theory and Chemical ReactionsExothermic and Endothermic Chemical ReactionsFactors That Influence Chemical Reaction RatesChemical EquilibriumEquilibrium ConstantsAltering Equilibrium Conditions: Le Châtelier’sPrincipleCopyright Cengage Learning. All rights reserved2Section 9.1Section 9.2Types of Chemical ReactionsRedox and Nonredox ReactionsChemical Reaction Process in which at least one new substance isproduced as a result of chemical change. Major types of chemical reactions– Combination– Decomposition– Displacement (single)– Exchange (double)– CombustionCopyright Cengage Learning. All rights reserved Oxidation-Reduction (Redox) Reaction– A chemical reaction in which there is atransfer of electrons from one reactant toanother reactant. Nonoxidation-Reduction (Nonredox) Reaction– A chemical reaction in which there is notransfer of electrons from one reactant toanother reactant.3Copyright Cengage Learning. All rights reserved4Section 9.1Section 9.1Types of Chemical ReactionsTypes of Chemical ReactionsCombination ReactionDecomposition Reaction A chemical reaction in which a single product isproduced from two (or more) reactants. A chemical reaction in which a single reactant isconverted into two (or more) simpler substances(elements or compounds).X Y XY (redox)XY X Y (redox)2H2 O2 2H2OCopyright Cengage Learning. All rights reserved2H2O 2H2 O25Copyright Cengage Learning. All rights reserved61
5/8/2017Section 9.1Section 9.1Types of Chemical ReactionsTypes of Chemical ReactionsDisplacement ReactionExchange Reaction (double displacement) A chemical reaction in which an atom ormolecule displaces an atom or group of atomsfrom a compound. A chemical reaction in which two substancesexchange parts with another and form twodifferent substances.X YZ Y XZ (redox)AX BY AY BX (non-redox)Na2SO4(aq) Pb(NO3)2(aq) 2NaNO3(aq) PbSO4(s)Zn 2HCl ZnCl2 H2Copyright Cengage Learning. All rights reserved7Copyright Cengage Learning. All rights reserved8Section 9.1Section 9.1Types of Chemical ReactionsTypes of Chemical ReactionsCombustion ReactionConcept Check A chemical reaction between a substance andoxygen (usually from air) that proceeds with theevolution of heat and light (usually from aflame).Classify each of the following chemical reactionsas a combination, decomposition, displacement,exchange, or combustion reaction.a) Mg(s) 2HCl(aq) MgCl2(aq) H2(g)C3H8 5O2 3CO2 4H2O (redox)b) HCl(g) NH3(g) NH4Cl(s)c) 4NH3 5O2 4NO 6H2OCopyright Cengage Learning. All rights reserved9Copyright Cengage Learning. All rights reserved10Section 9.1Section 9.2Types of Chemical ReactionsRedox and Nonredox ReactionsConcept CheckOxidation Number (Oxidation State)of an Element A number that represents the charge that anatom appears to have when the electrons ineach covalent/ionic bond it is participating in areassigned to the more electronegative of the twoatoms involved in the bond.E.g. NaCl made up of Na and Cl-Classify each of the following chemical reactionsas a combination, decomposition, displacement,exchange, or combustion reaction.a) Mg(s) 2HCl(aq) MgCl2(aq) H2(g)displacementb) HCl(g) NH3(g) NH4Cl(s)combinationH2O hasc) 4NH3 5O2 4NO 6H2O1 2- 1 H-O-HcombustionCopyright Cengage Learning. All rights reserved11Copyright Cengage Learning. All rights reserved122
5/8/2017Section 9.2Section 9.2Redox and Nonredox ReactionsRedox and Nonredox ReactionsRules for Assigning Oxidation NumbersExercise1. Oxidation # of an element in its elemental state 0.2. Oxidation # of a monatomic ion charge on ion.3. Group 1A 1; Group IIA 2.4. Hydrogen 1 in covalent compounds.5. Oxygen 2 in covalent compounds (except in peroxideswhere it 1).6. In binary molecular compounds, the more electronegativeelement is assigned a negative oxidation# equal to its1 2- 1 charge in binary ionic compounds. H O H7. Sum of oxidation states 0 in compounds;8. Sum of oxidation states of an ion charge of the ion.Copyright Cengage Learning. All rights reservedFind the oxidation numbers for each of theelements in each of the following compounds: 13K2Cr2O7CO32MnO2PCl5SF4Copyright Cengage Learning. All rights reservedSection 9.2Section 9.2Redox and Nonredox ReactionsRedox and Nonredox Reactions14Exercise To determine whether a reaction is a redoxreaction or a nonredox reaction, look forchanges in the oxidation # of elements involvedin the reaction. Changes in oxidation # mean a transfer ofelectrons redox reaction.Find the oxidation numbers for each of theelements in each of the following compounds: K 1; Cr 6; O –2C 4; O –2Mn 4; O –2P 5; Cl –1S 4; F –1K2Cr2O7CO32MnO2PCl5SF4Copyright Cengage Learning. All rights reserved15Copyright Cengage Learning. All rights reservedSection 9.2Section 9.3Redox and Nonredox ReactionsTerminology Associated with Redox ProcessesReaction Between Calcium Metal and Chlorine GasRedox Characteristics In a redox reaction, one reactant undergoesoxidation, and another reactant undergoesreduction. Oxidation – a reactant loses one or moreelectrons; reducing agent. Reduction – a reactant gains one or moreelectrons; oxidizing agent.Ca Cl2 CaCl20Copyright Cengage Learning. All rights reserved016 2 –117Copyright Cengage Learning. All rights reserved183
5/8/2017Section 9.3Section 9.3Terminology Associated with Redox ProcessesTerminology Associated with Redox ProcessesCopyright Cengage Learning. All rights reserved19Copyright Cengage Learning. All rights reservedSection 9.3Section 9.3Terminology Associated with Redox ProcessesTerminology Associated with Redox ProcessesConcept Check20Concept CheckWhich of the following are oxidation-reductionreactions? Identify the oxidizing agent and thereducing agent.a)Zn(s) 2HCl(aq) ZnCl2(aq) H2(g)b)Cr2O72-(aq) 2OH-(aq) 2CrO42-(aq) H2O(l)c) 2CuCl(aq) CuCl2(aq) Cu(s)Which of the following are oxidation-reductionreactions? Identify the oxidizing agent and thereducing agent.a)Zn(s) 2HCl(aq) ZnCl2(aq) H2(g)b)Cr2O72-(aq) 2OH-(aq) 2CrO42-(aq) H2O(l)c) 2CuCl(aq) CuCl2(aq) Cu(s)a) Zn – reducing agent; HCl – oxidizing agentc) CuCl acts as the reducing and oxidizing agent.Copyright Cengage Learning. All rights reserved21Copyright Cengage Learning. All rights reservedSection 9.4Section 9.4Collision Theory and Chemical ReactionsCollision Theory and Chemical ReactionsCollision TheoryMolecular Collisions Molecular Collisions Activation Energy Collision Orientation The reactant molecules, ions, or atomsmust come in contact (collide) with oneanother in order for any chemical change tooccur.Copyright Cengage Learning. All rights reserved23Copyright Cengage Learning. All rights reserved22244
5/8/2017Section 9.4Section 9.4Collision Theory and Chemical ReactionsCollision Theory and Chemical ReactionsActivation EnergyCollision Orientation Minimum combined kinetic energy thatcolliding reactant particles must possess inorder for their collision to result in achemical reaction. Reaction rates are sometimes very slowbecause reactant molecules must beorientated in a certain way in order forcollisions to lead successfully to products.Copyright Cengage Learning. All rights reserved25Copyright Cengage Learning. All rights reservedSection 9.4Section 9.5Collision Theory and Chemical ReactionsExothermic and Endothermic Chemical Reactions26Exothermic Reaction A chemical reaction in which energy isreleased as the reaction occurs. Energy is a “product” of the chemicalreaction. Example – burning of a fuelReaction of NO2 and COto Produce NO and CO2Copyright Cengage Learning. All rights reserved27Copyright Cengage Learning. All rights reservedSection 9.5Section 9.5Exothermic and Endothermic Chemical ReactionsExothermic and Endothermic Chemical ReactionsExothermic ReactionExothermic Reaction28 Occurs when the energy required to breakbonds in the reactants is less than theenergy released by bond formation in theproducts.Copyright Cengage Learning. All rights reserved29Copyright Cengage Learning. All rights reserved305
5/8/2017Section 9.5Section 9.5Exothermic and Endothermic Chemical ReactionsExothermic and Endothermic Chemical ReactionsEndothermic ReactionEndothermic Reaction A chemical reaction in which a continuousinput of energy is needed for the reaction tooccur. Energy is a “reactant” of the chemicalreaction. Example – photosynthesis in plants Occurs when the energy required to breakbonds in the reactants is more than theenergy released by bond formation in theproducts. Additional energy must be supplied fromexternal sources as the reaction proceeds.Copyright Cengage Learning. All rights reserved31Copyright Cengage Learning. All rights reservedSection 9.5Section 9.6Exothermic and Endothermic Chemical ReactionsFactors That Influence Chemical Reaction RatesEndothermic ReactionChemical Reaction Rate32 The rate at which reactants are consumedor products produced in a given time periodin a chemical reaction.Copyright Cengage Learning. All rights reserved33Copyright Cengage Learning. All rights reservedSection 9.6Section 9.6Factors That Influence Chemical Reaction RatesFactors That Influence Chemical Reaction RatesFour Factors That Affect Reaction RatePhysical Nature of Reactants1. Physical nature of the reactants2. Reactant concentrations3. Reaction temperature4. Presence of catalysts Includes the physical state of each reactant(s, l, or g) and the particle size. When reactants are all the same physicalstate, reaction rate is generally fasterbetween liquid-state reactants thanbetween solid-state reactants and is fastestbetween gaseous-state reactants.Copyright Cengage Learning. All rights reserved35Copyright Cengage Learning. All rights reserved34366
5/8/2017Section 9.6Section 9.6Factors That Influence Chemical Reaction RatesFactors That Influence Chemical Reaction RatesPhysical Nature of ReactantsReactant Concentrations For reactants in the solid state, reactionrate increases as subdivision of the solidincreases. When the particle size of a solid isextremely small, reaction rates can be sofast than an explosion results. An increase in the concentration of areactant causes an increase in the rate ofthe reaction. There are more molecules of that reactantpresent in the reaction mixture; thuscollisions between this reactant and otherreactant particles are more likely.Copyright Cengage Learning. All rights reserved37Copyright Cengage Learning. All rights reservedSection 9.6Section 9.6Factors That Influence Chemical Reaction RatesFactors That Influence Chemical Reaction RatesReaction TemperaturePresence of Catalysts Reaction rate increases as the temperatureof the reactants increases. The increased molecular speed causesmore collisions to take place in a giventime. Catalyst – a substance that increases achemical reaction rate without beingconsumed in the chemical reaction. Increases reaction rates by providingalternative reaction pathways that havelower activation energies than the original,uncatalyzed pathway. Enzymes are the catalysts in the humanbody.Copyright Cengage Learning. All rights reserved39Copyright Cengage Learning. All rights reservedSection 9.6Section 9.7Factors That Influence Chemical Reaction RatesChemical EquilibriumPresence of CatalystsChemical Equilibrium3840 The state in which forward and reverse chemicalreactions occur simultaneously at the same rate. The concentrations of reactants and products nolonger change (but do not have to be equal). On the molecular level, there is frantic activity.Equilibrium is not static, but is a highly dynamicsituation.Copyright Cengage Learning. All rights reserved41Copyright Cengage Learning. All rights reserved427
5/8/2017Section 9.7Section 9.7Chemical EquilibriumChemical EquilibriumH2 I2H2 I2 2HI2HICopyright Cengage Learning. All rights reserved43Copyright Cengage Learning. All rights reservedSection 9.7Section 9.7Chemical EquilibriumChemical EquilibriumReversible ReactionConcept CheckConsider an equilibrium mixture in a closed vesselreacting according to the equation: A chemical reaction in which the conversion ofreactants to products (the forward reaction) andthe conversion of products to reactants (thereverse reaction) occur at the same time. All reactions are reversible (can go in eitherdirection) under right conditions.Copyright Cengage Learning. All rights reservedH2O(g) CO(g)H2(g) CO2(g)You add more H2O(g) to the flask. How does theconcentration of each chemical compare to itsoriginal concentration after equilibrium isreestablished? Justify your answer. Remove H2OCO(g) is decreased H2(g) CO2(g) are increased45Copyright Cengage Learning. All rights reservedSection 9.7Section 9.8Chemical EquilibriumEquilibrium ConstantsConcept CheckConsider an equilibrium mixture in a closed vesselreacting according to the equation:H2O(g) CO(g)44H2(g) CO2(g)46Equilibrium Constant A numerical value that characterizes therelationship between the concentrations ofreactants and products in a system at chemicalequilibrium.You add more H2 to the flask. How does theconcentration of each chemical compare to itsoriginal concentration after equilibrium isreestablished? Justify your answer. Remove H2(g)CO(g) is increased H2(g) CO2(g) are decreased.Copyright Cengage Learning. All rights reserved47Copyright Cengage Learning. All rights reserved488
5/8/2017Section 9.8Section 9.8Equilibrium ConstantsEquilibrium ConstantsConclusions About the Equilibrium ExpressionwA xB Square brackets refer to molar concentrations. Product concentrations are always placed in thenumerator. Reactant concentrations are always placed inthe denominator. The coefficients in the balanced chemicalequation determine the powers to which theconcentrations are raised. Keq is used to denote an equilibrium constant.yC zD[C] y [D] zKeq w[A] [B] xCopyright Cengage Learning. All rights reserved49Copyright Cengage Learning. All rights reservedSection 9.8Section 9.8Equilibrium ConstantsEquilibrium ConstantsConclusions About the Equilibrium ExpressionTemperature Dependence Only concentrations of gases and substances insolution are written in an equilibrium expression. The concentrations of pure liquids and puresolids, which are constants, are never includedin an equilibrium expression. Keq always has the same value at a giventemperature regardless of the amounts ofreactants or products that are present initially. If the temperature changes, the value of Keq alsochanges. For reactions where the forward reaction isexothermic, Keq decreases with increasing T. For reactions where the forward reaction isendothermic, Keq increases with increasing T.Copyright Cengage Learning. All rights reserved51Copyright Cengage Learning. All rights reservedSection 9.9Section 9.8Altering Equilibrium Conditions: Le Châtelier’s PrincipleEquilibrium ConstantsLe Châtelier’s PrincipleReaction Completeness If a stress is applied to a system in equilibrium,the system will readjust in the direction that bestreduces the stress imposed on the system. If more products have been produced as a resultof the disruption, the equilibrium is said to haveshifted to the right. When disruption causes more reactants to form,the equilibrium has shifted to the left. If Keq is large, the equilibrium system containsmore products than reactants. If Keq is small, the equilibrium system containsmore reactants than products.Copyright Cengage Learning. All rights reserved53Copyright Cengage Learning. All rights reserved5052549
5/8/2017Section 9.8Section 9.8Equilibrium ConstantsEquilibrium ConstantsEquilibrium PositionKeq and the Extent to Which a Chemical Reaction Has Taken Place Qualitative indication of the relative amounts ofreactants and products present when a chemicalreaction reaches equilibrium.Copyright Cengage Learning. All rights reserved55Copyright Cengage Learning. All rights reserved56Section 9.8Section 9.9Equilibrium ConstantsAltering Equilibrium Conditions: Le Châtelier’s PrincipleLe Châtelier’s PrincipleEffects of Changes on the System If a stress (a change) is applied to a system inequilibrium, the system will readjust in thedirection that best reduces the stress imposedon the system. If more products have been produced as a resultof the disruption, the equilibrium is said to haveshifted to the right. When disruption causes more reactants to form,the equilibrium has shifted to the left.1. Concentration Changes: The system will shiftaway from the added component. If acomponent is removed, the opposite effectoccurs.Copyright Cengage Learning. All rights reserved57Copyright Cengage Learning. All rights reserved58Section 9.9Section 9.9Altering Equilibrium Conditions: Le Châtelier’s PrincipleAltering Equilibrium Conditions: Le Châtelier’s PrincipleConcentration ChangesEffects of Changes on the System2. Temperature: Keq will change depending uponthe temperature (endothermic – heat is areactant; exothermic – energy is a product).Endothermic:wA xB HeatyC zDEndothermic:wA xBCopyright Cengage Learning. All rights reserved59Copyright Cengage Learning. All rights reservedyC z Heat6010
5/8/2017Section 9.9Section 9.9Altering Equilibrium Conditions: Le Châtelier’s PrincipleAltering Equilibrium Conditions: Le Châtelier’s PrincipleExothermic reactionEffects of Changes on the System[Blue]3. Pressure:a) The system will shift away from the addedgaseous component. If a component isremoved, the opposite effect occurs.b) Addition of inert gas does not affect theequilibrium position.c) Decreasing the volume shifts the equilibriumtoward the side with fewer moles of gas.[Red] HeatEffect of TemperatureChange on anEquilibrium MixtureCopyright Cengage Learning. All rights reserved61Copyright Cengage Learning. All rights reservedSection 9.9Section 9.9Altering Equilibrium Conditions: Le Châtelier’s PrincipleAltering Equilibrium Conditions: Le Châtelier’s Principle62Effects of Changes on the System4. Addition of Catalysts: Do not change theposition of an equilibrium; although equilibriumis established more quickly.To play movie you must be in Slide Show ModePC Users: Please wait for content to load, then click to playMac Users: CLICK HERECopyright Cengage Learning. All rights reserved63Copyright Cengage Learning. All rights reserved64Section 9.9Altering Equilibrium Conditions: Le Châtelier’s PrincipleEquilibrium Decomposition of N2O5To play movie you must be in Slide Show ModePC Users: Please wait for content to load, then click to playMac Users: CLICK HERECopyright Cengage Learning. All rights reserved6511
9.2 Redox and Nonredox Chemical Reactions 9.3 Terminology Associated with Redox Processes 9.4 Collision Theory and Chemical Reactions 9.5 Exothermic and Endothermic Chemical Reactions 9.6 Factors That Influence Chemical Reaction Rates 9.7 Chemical Equilibrium 9.8 Equilibrium Constant
Chemical Reactions Slide 3 / 142 Table of Contents: Chemical Reactions · Balancing Equations Click on the topic to go to that section · Types of Chemical Reactions · Oxidation-Reduction Reactions · Chemical Equations · Net Ionic Equations · Types of Oxidation-Reduction Reactions · Acid-Base Reactions · Precipitation Reactions
Lesson Overview Chemical Reactions and Enzymes Chemical Reactions and Enzymes. Lesson Overview Chemical Reactions and Enzymes Chemical Reactions A chemical reaction is a process that changes , or transforms, one set of chemicals into another by changing the
Chemical reactions called _ reactions give off heat. 5. Other reactions called _ reactions absorb heat and cool the immediate environment. 6. True or False. During all chemical reactions, a chemical change takes place that produces new substances with properties different than those of the original substances. .
The Major Classes of Chemical Reactions. 4.6 Elements in Redox Reactions 4.1 The Role of Water as a Solvent 4.2 Writing Equations for Aqueous Ionic Reactions 4.3 Precipitation Reactions 4.4 Acid -Base Reactions. 4.5 Oxidation -Reduction (Redox) Reactions 4.7
Types of Reactions There are five main types of chemical reactions we will talk about: 1. Synthesis reactions 2. Decomposition reactions 3. Single displacement reactions 4. Double displacement reactions 5. Comb
ii. acid–base neutralization reactions iii. oxidation–reduction or redox reactions. Q.3. What are the important aspects of redox reactions? Ans: Almost every element participate in redox reactions. The important aspects of redox reactions are as follows: i. Large number of natural, biological and industrial processes involve redox reactions .
Topic 8: Chemical Reactions Chemical Equations & Reactions (Chapter 8 in Modern Chemistry) Describing Chemical Reactions A chemical reaction is the process by which one or more substances are changed into one or more different substances. In any chemical reaction, the original substances are known as the
Best of the Best ELA Websites for Elementary Grades Special Thanks to Beth Dennis for sharing these websites Note: This document is saved in the District Share folder, under Library Media Centers. General ELA: ABCya! Arranged by grade level, this site contains a great set of computer based activities for grades K-5th. K & 1st grade have oral direction options. Holiday-oriented choices are .
