Popular in Course
verified elite notetaker
Popular in Department
This 5 page One Day of Notes was uploaded by Elizabeth Hayden on Tuesday September 9, 2014. The One Day of Notes belongs to a course at a university taught by a professor in Fall. Since its upload, it has received 49 views.
Reviews for CHAPTER20.pdf
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/09/14
Chapter 20 Concepts Review 1 Oxidation Reduction a Redox transfer of electrons from one reactant to another resulting in a change of charge or oxidation number state b Oxidation loss of election i Charge increases more positive ii LEO c Reduction gaining electrons i Charge decreases more negative ii GER d One reactant acts on the other i Oxidizingreducing agents e Oxidation Number i Charge the atom would have IF it were ionic ii THEORETICAL NUMBER 2 Determining Oxidation Number Rules a Elemental state charge is O b Monotamic ions have same charge on periodic table i N 3 Cl 1 etc c Sum of oxidation numbers must equal overall charge d Hydrogen i Nonmetal1 ii Metal 1 e Fluorine i ALWAYS 1 f Oxygen i Almost always 2 ii Peroxides 1 iii Superoxides 1 2 iv Compounds with Fluorine 1 2 OF2 2 1 O2F2 3 Types of Redox a Combination i Start out as O and end up with either negative or positive charge b Decomposition i Start out with charge and end up with 0 c Combustion i Mixed charges all throughout d Single Displacement i Activity order of metals and halogens ii Element in natural state substitutes for the cation in a different compound 4 Activity order of single displacement a Metals i Lists metals by oxidation ability easier to oxidize more active the metal ii REACTION TAKES PLACE WHEN FREE ELEMENT IS MORE ACTIVE HIGHER THAN OTHER b Halogens i FgtClgtBrgtI 5 Electrochemistry reactions a Spontaneous used of Electrochemical cells i Redox b Non Spontaneous electrolysis i Forces redox rxn to go in opposite of spontaneous reaction 6 Balance Redox Reactions a ONLY IN ACIDIC SOLUTIONS b Balance half reactions separately i ii iii iv Elements BESIDES H and O O by adding H2O H by adding H Charge by adding e c Electrons in half rxn must balance and cancel out multiply half rxn so they cancel d Add half rxn and cancel species on both sides e CHECK TO MAKE SURE CHARGE BALANCES 7 Redox and Voltaic Cells a Electrons move from oxidized to reduces b Solid dissolves and aqueous in compound begins to turn solid c VOLTAIC CELLS 1 iii iv vi vii viii ix Spontaneous redox rxn that produces electricity by separating two half rxns Transfers electrons through external pathway Electron ow produces electrical current used for work Contains two isolated half cells 2 electrodes 1 Anode oxidation 2 Cathode reduction Voltaic Cell Salt bridge allows ions to ow between half cells KVJ Voltmeter Electrolyte whos ions don39t WI WI react Anions anode Cations cathode bridge 39 Cu2aq A9aq Cuts 2Agaq gt cu2aq 2Ags Cus electrode Ags electrode 8 Why do electrons ow from anode to cathode a Difference in POTENTIAL ENERGY b Similar to water owing over waterfall c Ecell potential difference between two electrodes i Also known as cell voltage because Ecell is measured in volts ii Calculated reduction potentials 9 Standard Reduction Potentials Depends on concentration of solution Pressure of gases Temperatures Cant measure rxn cell potential of half reaction but can measure total cell potential standard or reference half reaction given table EcellEanodeEcathode i Switch signs of given in order to find oxidizedanode cell potential g DOESN39T DEPEND ON COEFFICIENTS h MORE POSITIVE value of Ereduced GREATER DESIRE TO BE REDUCED i Cathode is always more positive than the anode 10 More Positive Value Of Er a Greater desire to be reduced b Stronger oxidizing agent c Strong oxidizing agents reduce to substances that are weak reducing 11 Any reaction that produces a positive emf will be spontaneous a E gt0 spontaneous b Elt0 nonspontaneous 12 Criteria for Spontaneity Ecellgt0 AGlt0 AS universe gt0 Kgt 1 13 Relationship between E and G a AG nFE 14 Relationship between E and K a E RTlnK nF where F is 96500 V mol 15 Nernst Equations a Voltaic cells discharge making conc of reactants and products change i Emf drops until E0 known as dead cell Concentrations are constant b Equation for NON STANDARD CONDITIONS c E E m3T92logQ 16 Batteries 539 P9amp7 3975 995 a Portable self contained voltaic cell b Cathode and anode c If connected in a series voltage would be the sum of each cells emf 17 Lead Acid Battery a 12V car battery b Requires 6 voltaic batteries in series c Can be recharged secondary d Electrodes immersed in H2S04 i Cathode Pb02 Anode Pbs 18 Alkaline Battery a Most common non chargeable battery b Cathode Mn02 and graphite c Anode Zns concentrated in KOH 19 Nickel Cadmium Battery a Portable electronic devices rechargeable b Cathode Ni00H c Anode Cds d Toxic environmental hazard dense 20 Nickel Metal Hydride a Cathode Ni00H b Anode ZrNi absorbs H atoms c Small rechargeable more frequent charging hybrid gas electric battery 2 1 Lithium ion Battery a Phone laptop batteries b Light great energy density c Cathode LiCo02 d Anode Li inserted into solid layers like graphite 22 Fuel Cells a Thermal energy released by combustion of fuels can be converted to electrical energy i H20 to steam drives turbine which drives electrical generator ii 40 energy efficient rest is lost to heat b Produce electricity from fuels by voltaic cell i Not batteries ii 2x more efficient than combustion 23 Hydrogen Fuel Cells a H2 and 02 gas oxidizing agent b Semi permeable membrane can act as a salt bridge allowing protons through and not electrons allowing high temperatures c Issues i Kinectic rxn too slow ii Need to stack cells for power iii Costly 24 Current research a Improving electrolytes and catalysts b Fuels that are easier to handle distribute hydrocarbons and alcohols
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'