Standard Electrodes
Definition and meaning of Standard Electrodes in chemistry.
Standard electrodes are reference electrochemical half-cells with a known, highly stable electrode potential that is used to reliably measure the relative potentials of other electrochemical cells.
In more detail
The universally accepted primary reference is the Standard Hydrogen Electrode (SHE), which is arbitrarily assigned a potential of exactly zero volts at standard thermodynamic conditions. Because the SHE is difficult to set up and safely maintain, secondary standard electrodes like the saturated calomel electrode (SCE) or the silver-silver chloride (Ag/AgCl) electrode are far more commonly used in laboratory settings. These reliable reference electrodes maintain a constant electrical voltage, allowing analytical chemists to accurately determine the unknown potential of a working electrode in a completed circuit. They are absolutely essential components in daily analytical techniques such as potentiometry and routine pH measurement.
Key facts
| Field | Analytical Chemistry |
|---|---|
| Primary Standard | Standard Hydrogen Electrode (SHE) |
| SHE Potential | 0.00 V |
| Common Secondary Standard | Ag/AgCl electrode |
A compact silver-silver chloride (Ag/AgCl) standard electrode is routinely utilized as a stable reference inside commercial pH meters to help determine the exact acidity of a chemical solution.
Frequently asked questions
Why isn't the standard hydrogen electrode used for everyday laboratory measurements?
The SHE requires continuous bubbling of highly flammable hydrogen gas and highly acidic solutions, making it impractical and hazardous for routine laboratory use compared to solid-state alternatives.