Lecture 2: Cell Potential

Cell Potential

The difference in Potential Energy between the Anode and Cathode in a voltaic sell. This depends on the relative ease with which the oxidizing agent is reduced at the Cathode and the reducing agent is oxidized at the Anode. The Cell Potential under standard conditions is called Standard EMF EE^{\circ } cell.

Strong Reducing \rightarrow ++

Strong Oxidizing \rightarrow -


  • Current - amp
  • Time - sec
  • Potential - volts
  • Charge - C
  • Energy - J

E(V)E^{\circ } (V) - Electrochemical series, given by standard reduction potential

The one on the top is Cathode. The one on the bottom is Anode.

To make a cell. (electrochemical cell) In the series.

EMF = Electromotive Force

Ecell=EcathodeEanodeE^{\circ }_{cell}= E_{cathode}-E_{anode}

ΔG=nFE\Delta G = -nFE ΔG=nFE\Delta G^{\circ } = -nFE^{\circ }

ΔG=ΔG+RTlnQ\Delta G = \Delta G^{\circ }+RTlnQ

nFE=nFE+RTlnQ-nFE = -nFE^{\circ }+ RTlnQ

E=ERTnFlnQE=E^{\circ }-\frac{RT}{nF}lnQ

At Equilibrium : Q=KQ=K E=OE=O ΔG=O\Delta G = O

E=RTnFlnKE^{\circ }=\frac{RT}{nF}lnK

  • FeF_{e} and CI2CI_{2} are strong oxidizing agents
  • Li and Na are more reducing, very reactive (Prefer to be Li+andNa+Li^{+} and Na^{+}
  • Cu2+:0.34Cu^{2+}:0.34
  • Zn+2:0.76Zn^{+2}: -0.76
  • H3O:OH_{3}O : O

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