Unit Fourteen: Redox Reactions

Unit Fourteen: Redox Reactions

Deals with the relation of the flow of electric current to chemical changes and the conversion of chemical to electrical energy (Electrochemical Cell) and electrical to chemical energy (Electrolysis) A device that can create electrical current from a

spontaneous redox reaction Electrodes: Anode oxidation occurs (- in chemistry) Cathode reduction occurs (+ in chemistry) Salt bridge saturated salt solution that connects the two half-cells

Cell notation shorthand form used to describe the cell Zn | Zn2+ | | Cu2+ | Cu | separation of electrode and ions | | salt bridge

Electrons are produced by oxidation of Zinc at anode. The electrons are used by Cu2+ for reduction at the cathode. The electrochemical cell dies when the anode is used up Cations migrate toward cathode and

anions migrate toward anode Mg and Cu Determine anode: Mg cathode: Cu Cell voltage: Mg Mg2+ + 2eE = 2.37 V Cu2+ + 2e- Cu E = 0.34 V

Mg + Cu2+ Mg2+ + Cu E = 2.71 V Cell notation: Mg | Mg2+ | | Cu2+ | Cu E = 2.71 Pb and Cu Ni and Fe

Found in most automobiles Consist of six electrochemical cells wired in series Each cell produces 2 volts for a total of 12 volts Each cell contains a porous lead anode where

oxidation occurs according to the following reaction Pb(s) + SO42-(aq) PbSO4(s) + 2e- (oxidation) PbO2(s) +4 H+(aq) + SO42-(aq) + 2e- PbSO4(s) + 2H2O(l) (reduction) The anode and cathode are immersed in H2SO4 and are coated with PbSO4 as the

electrical current is drawn. The battery goes dead when too much PbSO4 develops. Recharged by running the electrical current in reverse.

The reactants are constantly replenished Most common is the hydrogen-oxygen fuel cell Hydrogen gas flows past the anode and undergoes oxidation. Oxygen flows past the cathode and undergoes reduction. The sum of the two half reactions only product produced is water.

The fuel constantly flows trhrough the battery, generating electrical current as they undergo a redox reaction. Electrical current is used to drive an otherwise nonspontaneous redox reaction.

Electrolytic Cell an electrochemical cell used for electrolysis Used to produce metals from metal oxides and to plate metals onto other metals. Silver is being oxidized on the left side and reduced on the right. As it is reduced, it is deposited on the object to be plated.

Most common is the rusting of iron 2 Fe(s) 2 Fe2+(aq) + 4eO2(g) + 2 H2O(l) + 4e- 4 OH-(aq) 2 Fe(s) + O2(g) + 2 H2O(l) 2 Fe(OH)2(s) The Fe(OH)2 undergoes several additional reactions to for Fe2O3 (orange substance called rust).

Preventing rust Keep dry (rust cannot occur without moisture) Coat iron with substance impervious to water Sacrificial electrode Must be composed of metal above iron in activity series Sacrificial electrode oxidizes in place of iron Galvanized

Coat iron with a metal above itself on the activity series Zinc, for example, will oxidize before iron. Zinc oxide does not crumble, so it remains on the iron as a protective coating.

Recently Viewed Presentations

  • Specialty Plastics

    Specialty Plastics

    LCP This was followed in 1972 by Ekkcel 1-2000 from Carborundum which was Thermotropic (melt-processable) in nature Development work commenced in 1975 by Celanese led in the mid eighties to Vectra (now a Hoechst product) based on thermotropic polyester. LCP...


    The bustling town of Pompeii on the Bay of Naples was buried in ash by the eruption of Mt. Vesuvius in 79 C.E. Archaeologists have unearthed the streets, stores, and houses of this typical Roman town. Shops such as this...
  • The information contained in this session may contain ...

    The information contained in this session may contain ...

    Do not use public Internet access points. Reconcile Accounts Daily. Note any changes in the performance of your computer. Dramatic loss of speed, computer locks up, unexpected rebooting, unusual popups, etc. Make sure that your employees know how and to...
  • Q1 - Standing Waves Tension wave Wave on

    Q1 - Standing Waves Tension wave Wave on

    General Physics 2 Induction * General Physics 2 Waves & Sound * Reflection & Transmission when end is fixed, reflected wave in inverted when end is free to move, reflected wave is not inverted General Physics 2 Waves & Sound...
  • Review of Different Technologies and Devices

    Review of Different Technologies and Devices

    Review of Different Technologies and Devices. Quality Of Medical Products and Public Health. Boston University. ... The app software's algorithm will determine if the sample spectra matched the libraries spectra. ... Spectroscopy is one of the fastest analysis techniques.
  • Asl 2 Lesson/ Summer Assignment

    Asl 2 Lesson/ Summer Assignment

    Quietly at your desks, brain storm about what you did this summer and write down vocabulary that is related to activities you did during your break. Circle. the words you have trouble remembering how to sign or want to learn....
  • Dogsbody - Medicine, Nursing and Health Sciences

    Dogsbody - Medicine, Nursing and Health Sciences

    EPSE & NMS Sue Henderson Low Potency V High Potency Extra pyramidal side effects (EPSE) Acute dystonias: Oculogyric crisis, Torticollis, Lock jaw, Laryngeal spasm, Opisthotonos Akathisia Parkinsonism (Rigidity, bradykinesia, tremor) Tardive dyskinesia Dystonia: Oculogyric Crisis Muscles that control eyes movements...
  • PowerPoint to accompany Medical Language for Modern ...

    PowerPoint to accompany Medical Language for Modern ...

    Prefix, root, and suffix can be revealed on a mouse click. ag- (ad-) to, -glutin- stick, -ate composed of, pertaining to The definition of agglutinate is to stick together or clump. hem/o- blood, -globin/o- protein, -pathy disease A hemoglobinopathy is...