Electrode Potential And Its Applications

Prepared by Saba Shahzadi

Course CoordinatorDr. Shahnaz Rashid

Topics to be learned…. Electrode Potential (definition) Introduction to Electrochemistry Electrochemical cells ElectrodesElectrode potentialConcept of electrode potentialHalf cell reactionsTypes of electrode potentialsCell Potential or E.M.F and its difference from Potential

DifferenceDependence of Electrode PotentialMeasurement of Electrode PotentialElectrochemical SeriesApplications of Electrode Potential

Electrode Potential

Electrode potential is the voltage that an electrode is at , this has to measured versus a reference electrode.

Electrode potential is electromotive force of a cell that has two electrodes.

Introduction to Electrochemistry

Electrochemistry is a branch of chemistry which involves the interconversion of electrical and chemical energy.

These conversions are carried out through electrochemical cells.

Electrochemical CellsThere are two main types of electrochemical

cells Voltaic or Galvanic CellElectrolytic CellThe concept of electrode potentials could be

understand by the composition of any one of the above.

Construction of Electrochemical cell

What are Electrodes?

Electrodes are the means by which liquid and living organisms are included in electrical circuits.

There are two electrodes in each electrochemical cell.

It may be a metal or a solid substance (mixture)Its characteristics depend on the metal or solid

and the solution in which it is dipped.

Electrode Potential

The electrical potential difference set up between the metal and its solution is known as electrode potential.

Half Cell ReactionsBoth of the half cells have their own

individual electrode potential because two different type of reaction take place on them.

At anode oxidation reaction occurs. At cathode reduction reaction occurs. Zn+2 + 2e- Zn

Concept of Electrode PotentialDouble layer Formation: The deposition of negative charges on

the electrode when the chemical potential of copper’s ions in the metal is less than the chemical potential of the copper ions in solution then at the dipping of electrodes some quantity of the copper ions are hydrated and transferred to the metal which forms a positive charge on metal surface.

These processes cause the double electrical layer.

Double Layer

1- metal2 - solution

Types of electrode potentialOxidation Potential

Reduction potential

Standard cell potential (standard hydrogen electrode)Cell potential

Cell Potential and its difference from potential difference

The difference between the electrode potentials of the two electrodes constituting an electrochemical cell is known as electromotive force (e.m.f.) or cell potential of

a cell.

Dependence of Electrode PotentialConcentration

Temperature

Pressure (in case of gases only)

Measurement of Electrode potentialElectrode potential can never b measured

directly it can only be measured by Comparing an electrode with a standard or

reference electrode.

These electrodes may be S.H.E or calomel electrode.

Electrochemical series

Applications of electrode PotentialDetermination of Relative strengths of oxidizing and reducing

agents.Thermodynamic cell potentialUnknown concentrationpHFree energyEquilibrium constantSolubility productsDissociation constantTitration curve

Continued…

Predict theDirection of electron flowFeasibility of the reactionWeather a metal can liberate hydrogen from

acid or not