CHAPTER 12: Redox Reactionsand Electrochemistry Recall “GERtrude and LEO”Gain of Electrons ReductionLoss of Electrons OxidationGoals of Chapter:– Understand redox reactions in detail– Review oxidation numbers– Learn electrochemical techniques Application of Redox Chemistry – extracting metals fromores, e.g. 2 400 4Cu2CO3(OH)2(s) C(s) Æ 2Cu(s) 2CO2(g) H2O(g)“azurite” Need to learn to balance tricky redox reactionsCHEM 1310 A/B Fall 2006
Balancing Redox Equations Book provides a very schematic, step-bystep approach. Take a look at it. We’ll take a more freestyle approach. Let’s do the first example in the book. Balance:S2O62- (aq) HClO2 (aq) Æ SO42- (aq) Cl2(g)CHEM 1310 A/B Fall 2006
Strategies for Balancing RedoxEquationsS2O62- (aq) HClO2 (aq) Æ SO42- (aq) Cl2(g) General Strategy––––Divide equation into two half-reactionsOne reaction for reductionOne reaction for oxidationBalance each separately then recombine Another Trick– Assuming reactions in aqueous solution, H2O can bethrown in to the equation when needed (might not begiven!!)– H can be helpful for acidic solutions– OH- can be of use in basic solutionsCHEM 1310 A/B Fall 2006
Back to the ExampleS2O62- (aq) HClO2 (aq) Æ SO42- (aq) Cl2(g) First break into half-reactions Whatelement is reduced? What is oxidized?Reduced:Oxidized:CHEM 1310 A/B Fall 2006
Begin the Balancing ActS2O62- (aq) HClO2 (aq) Æ SO42- (aq) Cl2(g) Now balance the non-H, non-O atoms foreach SO42-CHEM 1310 A/B Fall 2006
Balance H and O’sS2O62- (aq) HClO2 (aq) Æ SO42- (aq) Cl2(g) Now throw in H2O, H (if acidic), OH- (ifbasic) as needed to balance the H and Oatoms. Here acidic (HClO2).Reduction:Oxidation:2HClO2 Æ Cl2S2O6 Æ 2SO42-CHEM 1310 A/B Fall 2006
OverviewS2O62- (aq) HClO2 (aq) Æ SO42- (aq) Cl2(g)Break into half-reactions: 1 3 -2Reduced:Oxidized:0HClO2 Æ Cl2 5 -2S2O62- 6 -2Æ SO42-Balance Cl, S:2HClO2 Æ Cl2S2O62- Æ 2SO42Balance H, O:6H 2HClO2 Æ Cl2 4H2O2H2O S2O62- Æ 2SO42 4H Combine the halves balance electrons first!CHEM 1310 A/B Fall 2006
Balancing Electrons Add and subtract electrons to make charge balance onboth sides of equation (seem strange? Don’t worry, justtemporary for book keeping!)6H 2HClO2 Æ Cl2 4H2OH2O S2O62- Æ 2SO42 4H Multiply one of the equations to obtain equal number ofelectrons. Then, add to cancel out electrons.Reduction:Oxidation:6H 2HClO2 Æ Cl2 4H2OH2O S2O62- Æ 2SO42 4H Final: Check: everything balanced?CHEM 1310 A/B Fall 2006
Another Practice ProblemAsO33- (aq) Br2 (aq) Æ AsO43- (aq) Br- (aq)I.II.III.IV.V.**assume basicIdentify what’s oxidized and what’s reducedSplit oxidation and reduction reaction,balance for all atoms but O,HAdd H2O, H , OH- to balance H,OAdd electrons to balance charge for halfreactionAdd half-reactions together to cancelelectronsCHEM 1310 A/B Fall 2006
Another Practice ProblemAsO33- (aq) Br2 (aq) Æ AsO43- (aq) Br- (aq)CHEM 1310 A/B Fall 2006**assume basic
Disproportionation The same chemical species is bothoxidized and reduced. e.g.,Cl2 (aq) Æ ClO3- (aq) Cl- (aq)[unbalanced] In these cases, a single species is allowedto appear in both half-reactions.Cl2 Æ ClO3Cl2 ÆCl-CHEM 1310 A/B Fall 2006[unbalanced]
Application to Batteries Batteries work by using redox reactions. Example of an electrochemical cell:Cu(s) 2Ag (aq) Æ Cu2 (aq) 2Ag(s) Above equation is balanced – recallexample of deposition of Ag(s) on copperwire in AgNO3 solution. Batteries harness the flow of electrons inredox reactions to perform electrical work.CHEM 1310 A/B Fall 2006
A Look Inside a Battery Electrons are produced atthe anode by oxidation.They flow to the ( )cathode, where theypromote reduction. Salt bridge allows flow ofions to keep chargeneutrality of solutions. Amount of charge flowcan be measured by:I Q/tcurrent charge/timeamperes (A) Coulombs/secCHEM 1310 A/B Fall 2006
Example Problem How many amps would be needed to reduce 1 mol ofAg ions in one hour? I Q/t To reduce a mol of Ag , one mol of e- is needed.CHEM 1310 A/B Fall 2006
Example Problem 2 A galvanic cell generates an average current of 0.121 Afor 15.6 min. The cathode half-reaction in the cell isPb2 (aq) 2e- Æ Pb(s). What mass of lead is depositedat the cathode?CHEM 1310 A/B Fall 2006
Electrometallurgy Electrochemical methods to producemetals from compounds (often ores) Uses redox reactions. e.g.,2Al2O3 3C Æ 4Al 3CO2MgCl2(l) Æ Mg(l) Cl2(g)Dangerous process!!Converted to HCl.CHEM 1310 A/B Fall 2006
Electrorefining Purify metals byelectrochemistry. Metals leave anode(where they’re oxidized)as ions and re-deposit oncathodes. Impurities are more likelyto stay in solution.CHEM 1310 A/B Fall 2006
Electroplating Use of electrochemistry to deposit a thinfilm of a metal (like Ag, Au) on top ofanother substance.CHEM 1310 A/B Fall 2006
CHAPTER 12: Redox Reactions . Goals of Chapter: - Understand redox reactions in detail - Review oxidation numbers - Learn electrochemical techniques Application of Redox Chemistry - extracting metals from ores, e.g. Need to learn to balance tricky redox reactions Cu 2CO 3(OH) 2(s) C(s) Æ2Cu(s) 2CO 2(g) H 2O(g .
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 .
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
The above example described a single-replacement reaction. All reactions of this kind are redox . A series of reactions are attempted. For each attempt, it is recorded whether a reaction occurs or not. . Worksheet 1. The following reactions were performed. Construct a redox table.
Part One: Heir of Ash Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26 Chapter 27 Chapter 28 Chapter 29 Chapter 30 .
Special Topic 6.1: Oxidizing Agents and Aging 6.2 Oxidation Numbers Internet: Balancing Redox Reactions 6.3 Types of Chemical Reactions Combination Reactions Decomposition Reactions Combustion Reactions Special Topic 6.2: Air Pollution and Catalytic Converters Single-Displacement Reactions Internet: Single-Displacement Reaction 6.4 Voltaic Cells
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
Most of these reactions can be classified into one of three main types of chemical reactions: precipitation reactions, acid-base neutralization reactions, and oxidation-reduction (also called “redox”) reactions. Aqueous Solutions(aq) Many reactions occur in an aqueous environment (i.e.,
Recent advances in development of organic and organometallic redox shuttles for lithium-ion redox flow batteries Thuan-Nguyen Pham-Truong[b], Qing Wang[c], Jalal Ghilane*[a] and Hyacinthe Randriamahazaka*[a] Abstract: In the recent years, redox flow batteries especially lithium (RFBs) and derivatives have attracted a wide attention from academia to
OCR Chemistry A H432 Redox and Electrode Potentials p. 3 Method 2: Constructing redox equations using oxidation numbers We can balance a redox equation using oxid
DOI: 10.1002/ejic.201600908 Essay Redox-Active Anticancer Complexes Redox-Active Metal Complexes for Anticancer Therapy Pingyu Zhang[a] and Peter J. Sadler*[a] Abstract: The redox properties of both
Oxidation-Reduction Reactions 6.2 Oxidation Numbers. 6.3 Types of Chemical . Reactions. 6.4 Voltaic Cells. n many important chemical reactions, electrons are transferred from atom to atom. We are surrounded by these reactions, commonly called oxidation‑reduction (or . redox) reactions, inside and out.
DEDICATION PART ONE Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 PART TWO Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 .
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
reactions that involve loss of electrons are called oxidation reactions. Similarly, the half reactions that involve gain of electrons are called reduction reactions. It may not be out of context to mention here that the new way of defining oxidation and reduction has been achieved only by establishing a correlation between the behaviour of species
Types of redox reactions Combination reactions: 2 elements combine to form a compound. Metals usually lose electrons (are oxidized) 2 Fe (s) 3 Cl 2 (g) 2 FeCl 3 (s) [demo] Decomposition reactions: Compound breaks up into elements or simpler compounds 2 Ag 2O 4 Ag (s) O 2 (g) Oxygenation: Reaction of element or compound
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. .
Types of Organic ReactionsTypes of Organic Reactions 1. Addition Reactions: A1. Addition Reactions: A B C HO OH O O H 2O HO OH O O OH fumarate malate 2. Elimination Reactions: D E F HO OH O O H 2 HO OH O O succinate fumarate 3. Substitution Reactions: G-H I G-I
A) Oxidation-reduction reactions require oxygen as a reactant. B) Oxidation-reduction reactions are also called redox reactions. C) Reduction is the gain of electrons. D) Oxidation-reduction reactions involve the transfer of electrons from one substance to another. E) If one substance is oxidized, then another substance must be reduced. F .
From Ramsey/Sleeper Architectural Graphic Standards, 9th ed., The American Institute of Architects, 1994. 37 Overhangs Overhang variances are needed where curbs, sidewalks, and signage exist. Overhangs also come into effect where retaining walls are present. From Ramsey/Sleeper Architectural Graphic Standards, 9th ed., The American Institute of Architects, 1994. 38 Vertical Clearance Diagram .