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- Measuring Standard ElectrodeElectrodes are conductors, in the form of wires, rods or plates, through which current enters and leaves the electrolyte. When the current leaves the electrodes it is known as the cathode... More Potential
- Standard Electrode Potential of Copper Half-cell
- Standard Electrode Potential of Zinc Half-cell
To measure the standard electrode potential of metal ions, its electrode is connected to a standard hydrogen electrode via a salt bridge and a voltameter to show the readings. A salt bridge is an inverted U-tube containing a saturated solution of KNO3 or KCl, its function is that it allows the migration of ions between two electrodes.
Electrode potentials are measured under the following standard conditions:
(i) concentration of the electrolyteAn electrolyte is a substance that dissociates in water into charged particles called ions. Positively charged ions are called cations. Negatively charged ions are called anions. Simply, an electrolyte is a... More in 1.0 moldm-3
(ii) gaseous reactant at one atmospheric pressure
(iii) temperature of the cell at 25°C or 298K
Under these conditions, the electrode potential is called standard electrode potential Eo. The superscript (o) stands for the standard state.
Standard Electrode Potential of Copper Half-cell:
When the Cu2(aq)/Cu(s)half-cell is connected to the 2H+(aq)/H2(g) half-cell by a salt bridge the voltameter reads 0.34 Volts. This is the potential difference between the two half cells and it is known as the electromotive force (e.m.f) of the cell.
The half-cell reaction at the copper and hydrogen electrode shows that electrons flow from the hydrogen electrode to the copper electrode.
Reactions at the Electrodes:
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