DOCSLIB.ORG

Electrochemical Cells - Redox Reactions Can Be Used in a Controlled Manner to Make a Battery

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electrochemical Cells - Redox Reactions Can Be Used in a Controlled Manner to Make a Battery Chapter 17 Worksheet #2 Name __________________________ Electrochemical Cells - Redox reactions can be used in a controlled manner to make a battery. A galvanic cell (voltaic cell or battery) converts the chemical energy of the reactants into electrical energy. BATTERY: Anode - AN OX, RED CAT Cathode - Salt Bridge - A tube containing a salt (such as KCl or NaNO3) solution that is used to connect two half-cells in an electrochemical cell; allows the passage of ions (maintains charge neutrality), but prevents the mixing of half-cell electrolytes. Shorthand notation for a galvanic cell: Zn(s)│Zn2+(aq)║Cu2+(aq)│Cu(s) where the anode is on the left, the cathode on the right, │ indicates the interface between the metal and solution, and ║ indicates the salt bridge. In many cells, the electrode itself does not react but serves only as a channel to direct electrons to or from the solution where a reaction involving other species takes place. The electrode itself is unaffected. Platinum and graphite are inert in most (but not all) electrochemical reactions. The Cu electrode could be replaced by a platinum or graphite electrode in the Zn/Cu battery: Zn(s)│Zn2+(aq)║Cu2+(aq)│Pt(s) Construct a battery from the reaction: Cr(s) + Pb2+(aq) Cr3+(aq) + Pb(s) Construct a galvanic cell using platinum electrodes and the reaction: - - + 2+ 10 Br (aq) + 2 MnO4 (aq) + 16 H (aq) 5 Br2(ℓ) + 2 Mn (aq) + 8 H2O(ℓ) A salt bridge is not required in a battery in which the reactants are physically separated from each other. e.g.: Pb-storage battery Pb(s) + PbO2(s) + 2 H2SO4(aq) 2 PbSO4(s) + 2 H2O(ℓ) The lead-acid storage battery is conveniently recharged by applying a voltage in the reverse direction greater than the cell potential. 2 PbSO4(s) + 2 H2O(ℓ) Pb(s) + PbO2(s) + 2 H2SO4(aq) Different species have varying degrees of ability to be oxidized or reduced. For example, sodium is very easily oxidized while gold is oxidized with great difficulty. A tabulation of reduction half-reaction potentials is listed + o in your text on pages APP-28 to APP-30. These are measured with respect to the H /H2 electrode ( E = 0 ). When two half-cells are combined to make a galvanic cell, reduction will occur in the half-cell with the greater reduction potential (making it the cathode). Oxidation will occur in the other half-cell (making it the anode). The standard state cell potential (voltage or emf) is given by: E = E(reduction) + E(oxidation) OR E = Ered(cathode) - Ered(anode) - - + 2+ Determine E for: 10 Br (aq) + 2 MnO4 (aq) + 16 H (aq) 5 Br2(ℓ) + 2 Mn (aq) + 8 H2O(ℓ) Construct a galvanic cell for the reaction: 2 Al(s) + 3 Fe2+(aq) 2 Al3+(aq) + 3 Fe(s) (a) Determine the cell potential under standard state conditions. (b) Label the anode and the cathode. (c) Show the electron flow and the flow of ions from salt bridge. (d) Which electrode could be replaced by an inert electrode without affecting the battery's operation? (e) Write the shorthand notation for the cell. Determine the standard state potentials for the following reactions: (a) Cu(s) + 2 Ag+(aq) Cu2+(aq) + 2 Ag(s) 2- + 3+ 3+ (b) Cr2O7 (aq) + 14 H (aq) + 2 Al(s) 2 Cr (aq) + 2 Al (aq) + 7 H2O(ℓ) (c) 3 Mg2+(aq) + 2 Au(s) 3 Mg(s) + 2 Au3+(aq) Positive emf's (voltages) indicate a spontaneous process. A negative voltage indicates the reaction is spontaneous in the reverse direction. Name a species which will oxidize Al to Al3+ but not Pb to Pb2+. ___________ - - Name a species which will reduce Cl2 to Cl but not Br2 to Br . ___________ Name a species which is a better oxidizing agent than Cu2+. ____________ Name a species which is a better reducing agent than Zn. _____________ Since spontaneity is related to ΔGo, it follows that Eo is related to ΔGo: o o ΔG = -n E The charge on one electron is 1.602x10-19 coulombs. The charge on one mole of electrons is 96,485 coulombs. This quantity is called a Faraday (). coulombs joule = 96,485 = 96,485 mole volt mole A volt is a unit of electrical potential. An electrical potential of one volt indicates one coulomb of charge has an increase in energy of 1 joule. Determine ΔG (in kJ) for the reaction at 25oC: 2 Ag+(aq) + Fe(s) 2 Ag(s) + Fe2+(aq) Determine the equilibrium constant for the reaction at 25oC: Ca2+(aq) + 2 Na(s) Ca(s) + 2 Na+(aq) Nernst Equation: 푅푇 0.0257 퐸 = 퐸° − ln(푄) = 퐸° − ln(푄) 푛퐹 푛 Determine the cell potential for the following battery: Cr(s)│Cr3+(0.050 M)║Cu2+(1.50 M)│Cu(s) .
Load more

Recommended publications
  • Electrochemical Cells
    Electrochemical cells = electronic conductor If two different + surrounding electrolytes are used: electrolyte electrode compartment Galvanic cell: electrochemical cell in which electricity is produced as a result of a spontaneous reaction (e.g., batteries, fuel cells, electric fish!) Electrolytic cell: electrochemical cell in which a non-spontaneous reaction is driven by an external source of current Nils Walter: Chem 260 Reactions at electrodes: Half-reactions Redox reactions: Reactions in which electrons are transferred from one species to another +II -II 00+IV -II → E.g., CuS(s) + O2(g) Cu(s) + SO2(g) reduced oxidized Any redox reactions can be expressed as the difference between two reduction half-reactions in which e- are taken up Reduction of Cu2+: Cu2+(aq) + 2e- → Cu(s) Reduction of Zn2+: Zn2+(aq) + 2e- → Zn(s) Difference: Cu2+(aq) + Zn(s) → Cu(s) + Zn2+(aq) - + - → 2+ More complex: MnO4 (aq) + 8H + 5e Mn (aq) + 4H2O(l) Half-reactions are only a formal way of writing a redox reaction Nils Walter: Chem 260 Carrying the concept further Reduction of Cu2+: Cu2+(aq) + 2e- → Cu(s) In general: redox couple Ox/Red, half-reaction Ox + νe- → Red Any reaction can be expressed in redox half-reactions: + - → 2 H (aq) + 2e H2(g, pf) + - → 2 H (aq) + 2e H2(g, pi) → Expansion of gas: H2(g, pi) H2(g, pf) AgCl(s) + e- → Ag(s) + Cl-(aq) Ag+(aq) + e- → Ag(s) Dissolution of a sparingly soluble salt: AgCl(s) → Ag+(aq) + Cl-(aq) − 1 1 Reaction quotients: Q = a − ≈ [Cl ] Q = ≈ Cl + a + [Ag ] Ag Nils Walter: Chem 260 Reactions at electrodes Galvanic cell:
    [Show full text]
  • On the Electrochemical Stability of Nanocrystalline La0.9Ba0.1F2.9 Against Metal Electrodes
    nanomaterials Article Fluoride-Ion Batteries: On the Electrochemical Stability of Nanocrystalline La0.9Ba0.1F2.9 against Metal Electrodes Maria Gombotz 1,* , Veronika Pregartner 1, Ilie Hanzu 1,2,* and H. Martin R. Wilkening 1,2 1 Institute for Chemistry and Technology of Materials, Technical Universtiy of Graz, Graz 8010, Austria; [email protected] (V.P.); [email protected] (H.M.R.W.) 2 ALISTORE—European Research Institute, CNRS FR3104, Hub de l’Energie, Rue Baudelocque, 80039 Amiens, France * Correspondence: [email protected] (M.G.); [email protected] (I.H.) Received: 27 September 2019; Accepted: 23 October 2019; Published: 25 October 2019 Abstract: Over the past years, ceramic fluorine ion conductors with high ionic conductivity have stepped into the limelight of materials research, as they may act as solid-state electrolytes in fluorine-ion batteries (FIBs). A factor of utmost importance, which has been left aside so far, is the electrochemical stability of these conductors with respect to both the voltage window and the active materials used. The compatibility with different current collector materials is important as well. In the course of this study, tysonite-type La0.9Ba0.1F2.9, which is one of the most important electrolyte in first-generation FIBs, was chosen as model substance to study its electrochemical stability against a series of metal electrodes viz. Pt, Au, Ni, Cu and Ag. To test anodic or cathodic degradation processes we carried out cyclic voltammetry (CV) measurements using a two-electrode set-up. We covered a voltage window ranging from −1 to 4 V, which is typical for FIBs, and investigated the change of the response of the CVs as a function of scan rate (2 mV/s to 0.1 V/s).
    [Show full text]
  • Liquid Junction Potentials at Mixed Electrolyte Salt
    LIQUID JUNCTION POTENTIALS AT MIXED ELECTROLYTE SALT BRIDGES. A Thesis 2ubmitted in Part-Fulfilment of the Requirements for the Degree of Master of Science of Rhodes University. BY NOEL PHILLIP FINKELSTEIN. RHODES UNIVERSITY, GRAHAli-1STmVN. September, 1956. ( i) ACKNOJLEDGJ:!Ji.fuNTS. It is with sincere gratitude that the following acknowledgements are made: DR . E.T. VE~DISR , M.Sc., (S.A.); Docteur es Sciences Physiques (France), for his able dir$ction, guidance, and constant encoura~ement. PROFESSOR W.F. BA~KER, B.Sc., Ph.D., F.R.I.C. F.n.s.s. Af., for his encouragement and interest. PHOFESSOR J.A. GLEDHILL , Ph.D., (S.A.), Ph.D., (Yale), for long hours of in­ valuable discussion. Mr. F. van der VI/A Tim, for his skilful and patient assistance with the technical aspects of the work. Mr. D.A. CLUR, B.Sc., (Hons.) for much in­ valuable discusssion, and many useful suggestions. Mrs. J. FINKELSTbiN, for her assistance with the clerical side of the pre­ paration of the thesis. Mr. H.T. DREYER, who was responsible for the diagrams. THE SOUTH AFRICAN COUNCIL FOH SCI~NTI?IC AND INDUSTRIAL RESJ:;AllCH for a grant held during this research. ( ii) CONTENTS . £ (( 'i j . AC KNO':-.ILED£}]-1ENTS (1) 1. GLOSSARY OF ABBREVIATIONS AND SYMBOLS. 1. 2. INTRODUCTimT. 3 . 3. CRITICAL SURVEY ON PREVIOUS WORK ON LIQUID JUNCTION POTEN~IALS. 5· 3.1. The Theory of Liquid Junction Pot- entials . 5· 3. 2. The ~l i m ination of the Error due to Liquid Junction Potentials . g. 3~3. The Measurement of Liquid Junction Potentials .
    [Show full text]
  • Galvanic Cell Notation • Half-Cell Notation • Types of Electrodes • Cell
    Galvanic Cell Notation ¾Inactive (inert) electrodes – not involved in the electrode half-reaction (inert solid conductors; • Half-cell notation serve as a contact between the – Different phases are separated by vertical lines solution and the external el. circuit) 3+ 2+ – Species in the same phase are separated by Example: Pt electrode in Fe /Fe soln. commas Fe3+ + e- → Fe2+ (as reduction) • Types of electrodes Notation: Fe3+, Fe2+Pt(s) ¾Active electrodes – involved in the electrode ¾Electrodes involving metals and their half-reaction (most metal electrodes) slightly soluble salts Example: Zn2+/Zn metal electrode Example: Ag/AgCl electrode Zn(s) → Zn2+ + 2e- (as oxidation) AgCl(s) + e- → Ag(s) + Cl- (as reduction) Notation: Zn(s)Zn2+ Notation: Cl-AgCl(s)Ag(s) ¾Electrodes involving gases – a gas is bubbled Example: A combination of the Zn(s)Zn2+ and over an inert electrode Fe3+, Fe2+Pt(s) half-cells leads to: Example: H2 gas over Pt electrode + - H2(g) → 2H + 2e (as oxidation) + Notation: Pt(s)H2(g)H • Cell notation – The anode half-cell is written on the left of the cathode half-cell Zn(s) → Zn2+ + 2e- (anode, oxidation) + – The electrodes appear on the far left (anode) and Fe3+ + e- → Fe2+ (×2) (cathode, reduction) far right (cathode) of the notation Zn(s) + 2Fe3+ → Zn2+ + 2Fe2+ – Salt bridges are represented by double vertical lines ⇒ Zn(s)Zn2+ || Fe3+, Fe2+Pt(s) 1 + Example: A combination of the Pt(s)H2(g)H Example: Write the cell reaction and the cell and Cl-AgCl(s)Ag(s) half-cells leads to: notation for a cell consisting of a graphite cathode - 2+ Note: The immersed in an acidic solution of MnO4 and Mn 4+ reactants in the and a graphite anode immersed in a solution of Sn 2+ overall reaction are and Sn .
    [Show full text]
  • Chapter 13: Electrochemical Cells
    March 19, 2015 Chapter 13: Electrochemical Cells electrochemical cell: any device that converts chemical energy into electrical energy, or vice versa March 19, 2015 March 19, 2015 Voltaic Cell -any device that uses a redox reaction to transform chemical potential energy into electrical energy (moving electrons) -the oxidizing agent and reducing agent are separated -each is contained in a half cell There are two half cells in a voltaic cell Cathode Anode -contains the SOA -contains the SRA -reduction reaction -oxidation takes place takes place - (-) electrode -+ electrode -anions migrate -cations migrate towards the anode towards cathode March 19, 2015 Electrons move through an external circuit from the anode to cathode Electricity is produced by the cell until one of the reactants is used up Example: A simple voltaic cell March 19, 2015 When designing half cells it is important to note the following: -each half cell needs an electrolyte and a solid conductor -the electrode and electrolyte cannot react spontaneously with each other (sometimes carbon and platinum are used as inert electrodes) March 19, 2015 There are two kinds of porous boundaries 1. Salt Bridge 2. Porous Cup · an unglazed ceramic cup · tube filled with an inert · separates solutions but electrolyte such as NaNO allows ions to pass 3 through or Na2SO4 · the ends are plugged so the solutions are separated, but ions can pass through Porous boundaries allow for ions to move between two half cells so that charge can be equalized between two half cells 2+ 2– electrolyte: Cu (aq), SO4 (aq) 2+ 2– electrolyte: Zn (aq), SO4 (aq) electrode: zinc electrode: copper March 19, 2015 Example: Metal/Ion Voltaic Cell V Co(s) Zn(s) Co2+ SO 2- 4 2+ SO 2- Zn 4 Example: A voltaic cell with an inert electrode March 19, 2015 Example Label the cathode, anode, electron movement, ion movement, and write the half reactions taking place at each half cell.
    [Show full text]
  • Electrochemistry: Elektrolytic and Galvanic Cell Co08 Galvanic Series (Beketov, Cca 1860)
    1/26 Electrochemistry: Elektrolytic and galvanic cell co08 Galvanic series (Beketov, cca 1860): Li, Ca, Al, Mn, Cr Zn, Cd Fe, Pb, [H2], Cu, Ag, Au ≈ ≈ ⊕ Cell = system composed of two electrodes and an electrolyte. electrolytic cell: electric energy chemical reaction ! galvanic cell: chemical reaction electric energy ! reversible galvanic cell (zero current) Electrodes anode = electrode where oxidation occurs Cu Cu2+ + 2 e ! − 2 Cl Cl2 + 2 e − ! − cathode = electrode where reduction occurs 2 Cu + + 2 e Cu credit: Wikipedia (free) − ! Cl2 + 2 e 2 Cl − ! − Oxidation and reduction are separated in a cell. The charge flows through the circuit. 2/26 Anode and cathode co08 electrolytic cell galvanic cell '$ '$ - - ⊕&% &% ⊕ Cl2 Cu2+ Cu2+ Pt Cl ! ! 2 Cu Cl Cl − Cu − CuCl2(aq) CuCl2(aq) anode cathode anode cathode “anions go to the anode” 3/26 Galvanic cells: electrodes, convention co08 Electrodes(= half-cells) may be separated by a porous separator, polymeric mem- brane, salt bridge. Cathode is right (reduction) ⊕ Anode is left (oxidation) negative electrode (anode) positive electrode (cathode) ⊕ liquid junction phase boundary . (porous separator) j salt bridge .. semipermeable membrane k Examples: 3 Cu(s) CuCl2(c = 0.1 mol dm ) Cl2(p = 95 kPa) Pt j − j j ⊕ Ag s AgCl s NaCl m 4 mol kg 1 Na(Hg) ( ) ( ) ( = − ) j j j 1 NaCl(m = 0.1 mol kg ) AgCl(s) Ag(s) j − j j ⊕ 2 3 4 3 3 3 Pt Sn +(0.1 mol dm ) + Sn +(0.01 mol dm ) Fe +(0.2 mol dm ) Fe j − − jj − j ⊕ 4/26 Equilibrium cell potential co08 Also: electromotive potential/voltage, electromo- tive force (EMF).
    [Show full text]
  • Thin Films of Lithium Ion Conducting Garnets and Their Properties
    Thin films of lithium ion conducting garnets and their properties dem Fachbereich Biologie und Chemie der Justus-Liebig-Universität Gießen vorgelegte Dissertation zur Erlangung des Grades Doktor der Naturwissenschaften – Dr. rer. nat. – von Jochen Reinacher geboren am 07.09.1984 Gießen 2014 II Dekan / Dean Prof. Dr. Holger Zorn 1. Gutachter / Reviewer Prof. Dr. Jürgen Janek 2. Gutachter / Reviewer Prof. Dr. Bruno K. Meyer Arbeit eingereicht: 10.06.2014 Tag der mündlichen Prüfung: 11.07.2014 III IV Abstract Different lithium ion conducting garnet-type thin films were prepared by pulsed laser deposition. Of these garnet-type thin films Li6BaLa2Ta2O12, cubic Li6.5La3Zr1.5Ta0.5O12 (additionally stabilized by Al2O3) and cubic Li7La3Zr2O12 stabilized by Ga2O3 were investigated in more detail. Conductivity measurements of these thin films performed in lateral geometry showed total conductivities of σ = 1.7∙10–6 S∙cm–1, σ = 2.9∙10–6 S∙cm–1 and σ = 1.2∙10–6 S∙cm–1, respectively. Electrochemical impedance spectroscopy was performed in axial geometry (orthogonal to the substrate), revealing conductivities of –5 –1 σ = 3.3∙10 S∙cm for Li6BaLa2Ta2O12 which is comparable to the bulk conductivity of –5 –1 Li6BaLa2Ta2O12 (σ = 4∙10 S∙cm ). The comparatively low lateral conductivity of the garnet-type material could be increased to a maximum of σ = 2.8∙10–5 S∙cm–1 for multilayer structures of two different alternating garnet-type materials (Li6.5La3Zr1.5Ta0.5O12:Al2O3, Li7La3Zr2O12:Ga2O3). These investigations revealed a strong influence of the thin film microstructure on the total conductivity. Additionally the electronic partial conductivity of Li6BaLa2Ta2O12 as bulk and thin film material was determined.
    [Show full text]
  • Electrochemistry –An Oxidizing Agent Is a Species That Oxidizes Another Species; It Is Itself Reduced
    Oxidation-Reduction Reactions Chapter 17 • Describing Oxidation-Reduction Reactions Electrochemistry –An oxidizing agent is a species that oxidizes another species; it is itself reduced. –A reducing agent is a species that reduces another species; it is itself oxidized. Loss of 2 e-1 oxidation reducing agent +2 +2 Fe( s) + Cu (aq) → Fe (aq) + Cu( s) oxidizing agent Gain of 2 e-1 reduction Skeleton Oxidation-Reduction Equations Electrochemistry ! Identify what species is being oxidized (this will be the “reducing agent”) ! Identify what species is being •The study of the interchange of reduced (this will be the “oxidizing agent”) chemical and electrical energy. ! What species result from the oxidation and reduction? ! Does the reaction occur in acidic or basic solution? 2+ - 3+ 2+ Fe (aq) + MnO4 (aq) 6 Fe (aq) + Mn (aq) Steps in Balancing Oxidation-Reduction Review of Terms Equations in Acidic solutions 1. Assign oxidation numbers to • oxidation-reduction (redox) each atom so that you know reaction: involves a transfer of what is oxidized and what is electrons from the reducing agent to reduced 2. Split the skeleton equation into the oxidizing agent. two half-reactions-one for the oxidation reaction (element • oxidation: loss of electrons increases in oxidation number) and one for the reduction (element decreases in oxidation • reduction: gain of electrons number) 2+ 3+ - 2+ Fe (aq) º Fe (aq) MnO4 (aq) º Mn (aq) 1 3. Complete and balance each half reaction Galvanic Cell a. Balance all atoms except O and H 2+ 3+ - 2+ (Voltaic Cell) Fe (aq) º Fe (aq) MnO4 (aq) º Mn (aq) b.
    [Show full text]
  • Battery Technologies for Small Scale Embeded Generation
    Battery Technologies for Small Scale Embedded Generation. by Norman Jackson, South African Energy Storage Association (SAESA) Content Provider – Wikipedia et al Small Scale Embedded Generation - SSEG • SSEG is very much a local South African term for Distributed Generation under 10 Mega Watt. Internationally they refer to: Distributed generation, also distributed energy, on-site generation (OSG) or district/decentralized energy It is electrical generation and storage performed by a variety of small, grid- connected devices referred to as distributed energy resources (DER) Types of Energy storage: • Fossil fuel storage • Thermal • Electrochemical • Mechanical • Brick storage heater • Compressed air energy storage • Cryogenic energy storage (Battery Energy • Fireless locomotive • Liquid nitrogen engine Storage System, • Flywheel energy storage • Eutectic system BESS) • Gravitational potential energy • Ice storage air conditioning • Hydraulic accumulator • Molten salt storage • Flow battery • Pumped-storage • Phase-change material • Rechargeable hydroelectricity • Seasonal thermal energy battery • Electrical, electromagnetic storage • Capacitor • Solar pond • UltraBattery • Supercapacitor • Steam accumulator • Superconducting magnetic • Thermal energy energy storage (SMES, also storage (general) superconducting storage coil) • Chemical • Biological • Biofuels • Glycogen • Hydrated salts • Starch • Hydrogen storage • Hydrogen peroxide • Power to gas • Vanadium pentoxide History of the battery This was a stack of copper and zinc Italian plates,
    [Show full text]
  • Stability of Positive Electrolyte Containing Trishydroxymethyl Aminomethane Additive for Vanadium Redox Flow Battery
    Int. J. Electrochem. Sci., 7 (2012) 4388 - 4396 International Journal of ELECTROCHEMICAL SCIENCE www.electrochemsci.org Stability of Positive Electrolyte Containing Trishydroxymethyl Aminomethane Additive for Vanadium Redox Flow Battery Sui Peng1, Nangfang Wang1,2, Chao Gao1, Ying Lei1, Xingxing Liang1, Suqin Liu1,* , Younian Liu1 1 Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China 2 School of Chemistry and Chemical Engineering, Hunan Institute of Engineering, xiangtan 411104, China *E-mail: [email protected] Received: 10 March 2012 / Accepted: 24 March 2012 / Published: 1 May 2012 Trishydroxymethyl aminomethane (Tris) was used as an additive of the positive electrolyte for all vanadium redox battery (VRB) and cycling and electrochemical stabilities of the positive electrolyte were investigated. The 50 cyclic voltammetry (CV) cycles suggested that the positive electrolyte with the Tri additive after charge-discharge cycles has good cycle stability compared to that before the charge-discharge cycles. The VRB employing the vanadium electrolyte with the Tris additive as positive electrolyte exhibited better charge-discharge behavior and less discharge capacity fade rate with cycles compared with the blank electrolyte system. The UV/visible spectroscopy showed that the vanadium concentration in the positive electrolyte containing Tri additive during 40 charge-discharge cycles remains unchanged. The X-ray photoelectron spectroscopy (XPS) verified that the positive electrolyte with the Tri additive has no etching and oxidation effect on the carbon felt electrode. Keywords: Vanadium redox flow battery; additive; stability; electrochemical stability 1. INTRODUCTION All vanadium redox flow battery (VRB) is a promising energy conversion device that employs V(V)/ V(II)/V(III) and V(IV)/V(V) couples in the negative and positive half-cells respectively to store chemical potential energy [1-3].
    [Show full text]
  • Potato Power
    Potato Power Author: Nick Robertson Date Created: Spring 2008 Subject: Chemistry Level: Middle School Standards: New York State-Physical Setting/Chemistry (www.emsc.nysed.gov) Standard 1- Analysis, Inquiry and Design Standard 4 - The Physical Setting Standard 6 - Interconnectedness: Common Themes Standard 7- Interdisciplinary Problem Solving Schedule: One 60 minute period Objectives: Vocabulary: Understand what an electrochemical Voltaic cell Cathode cell is and how it can be used to Oxidation Anode power a small device. Reduction Materials: For Each Group: For Class: Covered wire with Voltmeter (optional) Students will: alligator clips at both ends. Build a voltaic cell using a potato Potatoes, apples, oranges, etc, for to power a small device. students to try Compare the effectiveness of Zinc strips or various types of fruits and galvanized nails vegetables in powering a small Copper strips or device. copper pennies Device to be powered Safety: This activity does not contain any safety concerns. Science Content for the Teacher: This lesson is based off of the concepts surrounding an electrochemical cell. There is an anode and a cathode that is separated by an electrolyte, and are connected by an electrically conducing wire. At the cathode, reduction occurs and at the anode, oxidation occurs. To determine the flow of electrons, the mnemonic device “LEO the lion goes GER” can be used. LEO means “loses electrons oxidized” and GER means “gains electrons reduction.” Therefore electrons are flowing from the anode to the cathode. Most general chemistry text books have very nice figures to demonstrate these concepts. For more information and pictures, visit http://mooni.fccj.org/~ethall/2046/ch18/galvanic.htm A common galvanic cell uses zinc and copper as the electrodes, which are the metals the students will use this project.
    [Show full text]
  • Energy Storage Outline Air Pollution
    Energy storage February 12, 2009 Outline Energy Storage • Review last week • Why do we store energy? Larry Caretto • What kind of energy is stored? Mechanical Engineering 496ALT • Fuels as energy storage Alternative Energy • Batteries • Thermal energy storage February 12, 2009 • Electrical energy storage • Mechanical energy storage 2 Air Pollution • Clean Air Act requirements – National ambient air quality standatds for criteria pollutanta • States must submit plans (state implementation plans or SIPs) to achieve standards by date – Toxic pollutants by separate process – Acid rain program by 1990 CAA amendment – Mobile vs stationary sources – Permitting requirements – Fossil fuel combustion biggest source 3 4 5 6 ME 496ALT – Alternative Energy 1 Energy storage February 12, 2009 Ozone Production Cap-and-Trade Programs • Emission requirements set for all sources in an area • Sources have three options – Comply with emission limits – Produce excess emissions and buy credits from others who generate credits – Reduce emissions beyond requirements to generate credits for sale • Alternative to “command and control” 7 8 Acid Deposition Results Ozone Layer and Greenhouse • Stratospheric ozone reduces UV radiation reaching planet’s surface • Chlorofluorocarbons (CFCs) reach stratosphere and destroy ozone • Natural balance between solar radiation reaching earth and IR radiation leaving • Balance upset by human activities producing “greenhouse gases”, espe- cially CO2 from fossil fuel combustion 9 10 IPCC 2007 reports Greenhouse Gases • Intergovernmental
    [Show full text]