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Definition of Standard hydrogen electrode

Standard hydrogen electrode Definition from Science & Technology Dictionaries & Glossaries
Electrochemistry Dictionary
"The most fundamental reference electrode in electrochemistry. ""By definition"" its equilibrium potential is considered zero at any temperature, because this electrode was chosen as an arbitrary zero point for electrode potentials. A zero point is needed since the potential of a single electrode cannot be measured, only the difference of two electrode potentials is measurable. All electrode potentials are expressed on this ""hydrogen scale."" It is a hydrogen electrode with an electrolyte containing unit concentration of hydrogen ions and saturated with hydrogen gas at unit atmosphere pressure. This electrode can be somewhat inconvenient to use because of the need to supply hydrogen gas. Therefore, other reference electrodes (e.g., calomel or silver/silver chloride) are often used instead, but the measured electrode potentials can be converted to the ""hydrogen scale."" Abbreviated as ""SHE."" Also called ""normal hydrogen electrode."" Strictly speaking, one must use unit activity rather than concentration of hydrogen ions and unit fugacity rather than unit pressure of hydrogen gas. "
General Chemistry Glossary
A platinum electrode that runs the half reaction 2 H+(aq, 1M) + 2 e- H2(g, 1 atm), chosen as a reference for cell voltages. The electrode potential of the standard hydrogen electrode is defined to be zero volts.
Standard hydrogen electrode Definition from Encyclopedia Dictionaries & Glossaries
Wikipedia English - The Free Encyclopedia
The standard hydrogen electrode (abbreviated SHE), is a redox electrode which forms the basis of the thermodynamic scale of oxidation-reduction potentials. Its absolute electrode potential is estimated to be 4.44 ± 0.02 V at 25 °C, but to form a basis for comparison with all other electrode reactions, hydrogen's standard electrode potential (E0) is declared to be zero at all temperatures. Potentials of any other electrodes are compared with that of the standard hydrogen electrode at the same temperature.

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