Standard hydrogen electrode
The requirements hydrogen electrode abbreviated SHE, is a specifications electrode potential E° is declared to be zero volts at any temperature. Potentials of all other electrodes are compared with that of a standard hydrogen electrode at a same temperature.
Hydrogen electrode is based on the redox half cell:
This redox reaction occurs at a platinized platinum electrode. The electrode is dipped in an acidic solution in addition to pure hydrogen gas is bubbled through it. The concentration of both the reduced pretend and oxidised make is submits at unity. That implies that the pressure of hydrogen gas is 1 bar 100 kPa as well as the activity coefficient of hydrogen ions in the sum is unity. The activity of hydrogen ions is their powerful concentration, which is cost to the formal concentration times the activity coefficient. These unit-less activity coefficients areto 1.00 for very dilute water solutions, but usually lower for more concentrated solutions. The Nernst equation should be statement as:
where: