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Electrodes and Electrodes and Electrochemical CellsElectrochemical Cells

Electrodes and Electrodes and Electrochemical CellsElectrochemical Cells

““Batteries”Batteries”

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Electric power conversion in electrochemistry

Chemical Reactions

Electric Power

Electrolysis / Power consumption

Electrochemical battery / Power generation

Types of the electrochemical system for electric power generation

Primary batteries

POWER

Fuel cells

Reaction products (exhaust)

Reductant (fuel)

Oxidant

POWER

Secondary batteries

Recharge

POWER

POWER

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Types of Electrode (Summery)

EElleeccttrrooddee TTyyppee DDeessiiggnnaattiioonn

MMeettaall//mmeettaall iioonn MM((ss))||MM++((aaqq))

GGaass PPtt((ss))||XX22((gg))||XX++((aaqq)) oorr PPtt((ss))||XX22((gg))||XX--((aaqq))

MMeettaall//iinnssoolluubbllee ssaalltt

MM((ss))||MMXX((ss))||XX--((aaqq))

RReeddooxx

PPtt((ss))||MM++((aaqq)),,MM22++((aaqq))

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Types of Electrode (continued)

RReeddooxx CCoouuppllee HHaallff rreeaaccttiioonn

MM++//MM MM++((aaqq)) ++ ee-- MM((ss))

XX++//XX22

XX22//XX--XX++((aaqq)) ++ ee-- ½½ XX22((gg))½½ XX22((gg)) ++ ee-- XX--((aaqq))

MMXX//MM//XX-- MMXX((ss)) ++ ee-- MM((ss)) ++ XX--((aaqq))

MM22++//MM++ MM22++((aaqq)) ++ ee-- MM++ ((ss))

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Simple Type:Anode| electrolyte | Cathode

Complex Type:A | Anolyte || Catholyte|C

Cell Conventions

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Cells Connections

Me1n+ SO4

2- Me2n+ SO4

2-

Me2

Me20 - ne- = Me2

n+

ANODE

Me2n+ - ne- = Me2

0

CATHODE

Salt Bridge

Me1

Principles of power generation in the electrochemical systems

Me1n+ SO4

2- Me2n+ SO4

2-

Me2

Me20 - ne- = Me2

n+

ANODE

Me2n+ - ne- = Me2

0

CATHODE

Me1 Diaphragm

Membraneor

Principles of power generation in the electrochemical systems

Pt|H2(g)| HCl | AgCl(s) ,Ag(s) .

H2 2H+ +2e AgCl+eAg+Cl-

Simple Cell

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Zn

Zn2+ ions

Cu

Cu2+ ions

wire

saltbridge

electrons

Zn

Zn2+ ions

Cu

Cu2+ ions

wire

saltbridge

electrons

Zn --> ZnZn --> Zn2+2+ + 2e- + 2e- CuCu2+2+ + 2e- --> Cu + 2e- --> Cu

<--Anions<--AnionsCations-->Cations-->

OxidationOxidationAnodeAnodeOxidationOxidationAnodeAnode RedReductionuction

CatCathodehodeRedReductionuctionCatCathodehode

RED CATRED CAT

Zn|Zn 2+||Cu 2+|Cu

Complex Cell

Pt | Fe 2+ ,Fe 3+ | | Ag+ | Ag

Copyright©2000 by Houghton Mifflin Company. All rights

reserved.

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Copyright©2000 by Houghton Mifflin Company. All rights

reserved.

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Zn|ZnSO4||HCL|H2,Pt

ZnZn 2++2e

H++2e H2

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Dry Cell Battery

ZnCl2

Anode Anode Zn ---> ZnZn ---> Zn2+2+ + 2e- + 2e-

Cathode Cathode 2 NH2 NH44++ + 2e- - + 2e- -22 NH NH33 + +

HH22