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The anode is written to the left, the cathode is to the right. One vertical line

indicates the "metal-solution" boundary; two vertical lines indicate "solution-

solution" boundary. The potentials difference between electrodes (φ) determines

the voltage E (electromotive force) of the galvanic element.

To calculate E from the value of the cathode potential it is necessary to subtract

the anode potential magnitude.

Е = φ к – φ а,
φ к - the cathode potential, V;

φ а - the anode potential, V.

The magnitude of the electrode potential depends on the temperature, and on

the metal ions concentration. This dependency of the electrode potential is

expressed by the Nernst equation:

0 RT n+
φ = φ + ln Me  ,


nF

0
where φ is the standard electrode potential, V.;
R universal gas constant, 8,31 J / mol • K;
T is temperature, K;

n is the number of electrons involved in the electrochemical process;

F is Faraday constant - 96,500 Кl / mol;

3
n+
[Me ] is the concentration of metal ions in the solution, mol · eq / dm .
If one switches from natural logarithms to decimal, then, for standard
conditions equation is as follows:

, 0 059
  0  lg Me n  
n

9.3 Electrolysis
The re-dox processes occurring on the electrodes due to the passage of a

constant electric current from an external source through a solution or a molten
electrolyte, they are called electrolysis.

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