Balance Redox Rxns: Fe(OH)3 + [Cr(OH)4]-1 Fe(OH)2 + CrO4-2

AP CHM HW Read: Chapter 18

Review the Multiple-Choice Section of the Midterm.

Electro-chemistry

The flow of electrons through a metal Metallic Conduction The flow of electrons through a metal

The movement of ions (electrolytes) through a solution Ionic Conduction The movement of ions (electrolytes) through a solution Electrolytic Conduct.

The surface or point in which oxidation or reduction takes place Electrode The surface or point in which oxidation or reduction takes place

The electrode where oxidation takes place Anode The electrode where oxidation takes place An Ox (-)

The electrode where reduction takes place Cathode The electrode where reduction takes place Red Cat (+)

Voltaic or Galvanic Cell Electrochemical Cell in which:

a spontaneous oxidation-reduction reaction produces electrical energy

A cell where only oxidation or only reduction takes place Half-Cell A cell where only oxidation or only reduction takes place

An electrochemical cell must have two half-cells connected by a salt bridge

A half-cell will not work by itself Both half-cells are required

) Allows electrical contact between the two half-cells Salt Bridge ) Allows electrical contact between the two half-cells

) Prevents mixing of the two half-cell solutions

) Allows ions to flow maintaining electrical neutrality

Determining the Redox Rxn & Voltage of an Electrochemical Cell

Identify all molecules & ions (reactants) that exist in the electrolytic cell

) Determine all possible half-reactions that could occur in the system

) Look up each half-rxn from the Std. Redox Tables

) Record each half-rxn & its standard voltage

) Save the oxidation half-rxn that has the highest voltage

) Save the reduction half-rxn that has the highest voltage

) Balance the electrons between the two half-rxns

) Add the two half-rxns to obtain the full electrochemical reaction

) Add the voltage of each half-rxn to obtain the std. voltage required

Determine Eo Zn(s) + 2 Ag+1(aq) 2 Ag(s) + Zn+2(aq)

AP CHM HW Read: Chapter 18 Problems: 7 & 15a Page: 526

REDOX Shorthand Zn|Zn+2||Ag+1|Ag ox red Zn||Zn|Zn+2||Ag+1|Ag||Pt an ox red cat

Drill: Determine Shorthand Rxn & voltage when Cu+1 is reacts with solid potassium

Voltaic Cell Problems

Determine all when a cell with a Cu electrode in CuCl2(aq) is connected to a cell with a Zn electrode in ZnBr2(aq)

Determine all when a cell with a Fe electrode in FeCl3(aq) is connected to a cell with a Mn electrode in MnCl2(aq)

Determine all when a cell with a Mg electrode in MgCl2(aq) is connected to a cell with a Au electrode in AuCl3(aq)

Drill: What is the best reducing agent on the chart?

Electrolysis Using electricity to force an, oh fooey, non-spontaneous electrochemical rxn

Chemical cell where electrolysis is being performed Electrolytic Cell Chemical cell where electrolysis is being performed

How to determine the Redox Rxn & voltage of an Electrolytic Cell

Identify all molecules & ions (reactants) that exist in the electrolytic cell

) Determine all possible half-reactions that could occur in the system

) Look up each half-rxn from the Std. Redox Tables

) Record each half-rxn & its standard voltage

) Save the oxidation half-rxn that has the highest voltage

) Save the reduction half-rxn that has the highest voltage

) Balance the electrons between the two half-rxns

) Add the two half-rxns to obtain the full electrochemical reaction

) Add the voltage of each half-rxn to obtain the std. voltage required

Determine the rxn that takes place when 1 Determine the rxn that takes place when 1.5 V is passed through two Pt electrodes in a solution containing MgI2(aq) & ZnCl2(aq)

AP CHM HW Read: Chapter 18 Problems: 23 Page: 527

Determine the rxn that takes place when 2.5 V is passed through two Pt electrode in a solution of NaCl(aq)

Determine the rxn that takes place when electricity is passed through two Pt electrode in molten NaCl

Drill: Determine the rxn that takes place when electricity is passed through two Pt electrodes in ZnCl2(aq)

A car battery has lead & lead(IV)oxide electrodes in an acidified aqueous lead(II)sulfate solution. Using the book, determine the voltage that can be produced.

Relating Equations DGo = DHo - TDSo DGo = -RTlnKeq DGo = -nFEo

Determine rxn, Eo, DGo, & Keq for a voltaic cell with half-cells containing Ni(s) in NiCl2(aq) & Sn(s) in SnCl2(aq).

for non-standard conditions Nernst Equation E = Eo - (RT/nF)lnQ for non-standard conditions

Determine the voltage of a cell with a silver electrode in 1 Determine the voltage of a cell with a silver electrode in 1.0 M AgNO3 & an iron electrode in 0.10 M FeCl2 at 27oC

Determine the voltage of a cell with a silver electrode in 1 Determine the voltage of a cell with a silver electrode in 1.0 M AgNO3 & a zinc electrode in 0.010 M ZnCl2 at 27oC

Drill: Determine the rxns that take place when 9.65 mA is passed for 2.5 Hrs through two Pt electrodes in a solution containing MnBr2(aq) & CuF2(aq)

Determine the voltage of a cell with a copper electrode in 0 Determine the voltage of a cell with a copper electrode in 0.10 M CuI & a zinc electrode in 1.0 M ZnCl2 at 27oC

Determine the voltage of a cell with a silver electrode in 0 Determine the voltage of a cell with a silver electrode in 0.10 M AgNO3 & a zinc electrode in 1.0 M ZnCl2 at 27oC

AP CHM HW Read: Chapter 18 Problems: 41 Page: 528

The test on electrochemistry will be on ____day.

Electroplating & Electro-purifying

Electrolysis During electrolysis, oxidation & degradation would occur at the anode while reduction & electroplating would occur at the cathode

Amount (mass, volume, moles, etc) can be determined from the charge Current Formula Current = charge/unit time Amps = coul/sec Amount (mass, volume, moles, etc) can be determined from the charge

Calculate the mass of copper plated onto the cathode when a 9 Calculate the mass of copper plated onto the cathode when a 9.65 mAmp current is applied to a solution of CuSO4 for 5.0 minutes.

Calculate the years required to plate 216 kg of silver onto the cathode when a 96.5 mAmp current is applied to a solution of AgNO3

Drill: Calculate the current required to purify 510 kg of aluminum oxide in 5.0 hours

Current, Mass, Time Formula: nFm = MWIt

Check HW

Test Tuesday

Balance the Rxn KMnO4 + HCl MnO2 + KClO2

Calculate the time required to electroplate 19 Calculate the time required to electroplate 19.7 mg of gold onto a plate by passing 965 mA current through a solution of Au(NO3)3

Determine the voltage of a cell with a silver electrode in 5 Determine the voltage of a cell with a silver electrode in 5.0 M AgNO3 & an zinc electrode in 0.25 M ZnCl2 at 27oC

Determine the rxn that takes place when 1 Determine the rxn that takes place when 1.0 V is passed through two Pt electrodes in a soln containing NaI(aq) & CoCl2(aq).

Calculate the time required to gold plate a 2 Calculate the time required to gold plate a 2.0 mm layer onto a plate (SA = 750 cm2) by passing 965 mA current through a solution of AuCl3 (DAu = 20 g/cm3)

Calculate the time required to purify a 204 kg of ore that is 60 Calculate the time required to purify a 204 kg of ore that is 60.0 % Al2O3 by applying a 965 kA current through molten ore sample:

Calculate the time required to purify a 32 kg of ore that is 75 Calculate the time required to purify a 32 kg of ore that is 75.0 % Fe2O3 by applying a 9.65 kA current through molten ore sample:

A voltaic cell with a silver electrode in 0 A voltaic cell with a silver electrode in 0.10 M Ag+ & a zinc electrode in 1.0 M Zn+2 at 27oC is allowed to react for 5.0 mins at 9.65 A. Calculate: Eo, E, DGo, & mass increase of the cathode.

A voltaic cell with a gold electrode in 0 A voltaic cell with a gold electrode in 0.0010 M Au+3 & a zinc electrode in 10.0 M Zn+2 at 27oC is allowed to react for 5.0 hrs at 9.65 A. Calculate: Eo, E, DGo, & mass increase of the cathode.