Knowra Standard hydrogen electrode Standard hydrogen electrode The standard hydrogen electrode is a reference electrode assigned a standard potential of zero volts. It uses hydrogen gas and an acidic solution in contact with platinized platinum.
Hydrogen electrode reaction : The reversible conversion between hydrogen ions and hydrogen gas, represented by 2H⁺ + 2e⁻ ⇌ H₂. This is the half-reaction whose potential the electrode defines as zero under standard conditions.
Standard state : A convention specifying reference conditions for thermodynamic quantities, including pressure, concentration, and temperature. The electrode's standard potential applies only when its components meet specified reference conditions.
Galvanic cell : An electrochemical cell that produces electrical energy from a spontaneous redox reaction. Pairing it with another half-cell lets the reference establish that cell's potential.
Saturated calomel electrode : A reference electrode based on mercury, mercurous chloride, and saturated potassium chloride solution. It is easier to handle routinely than a hydrogen-gas electrode, but its potential is not defined as zero.
Nernst equation : An equation relating an electrode potential to reaction composition, temperature, and the standard potential. It predicts how the hydrogen electrode's potential changes when its conditions depart from standard values.
Activity (chemistry) : An effective concentration that accounts for interactions among particles in a nonideal chemical system. Hydrogen-ion activity, rather than concentration alone, determines the electrode's equilibrium potential.
Potentiometry : An electroanalytical method that determines chemical information from measured voltage at negligible current. The electrode provides a stable reference for measuring potentials in potentiometric setups.
Silver chloride electrode : A reference electrode using silver in contact with silver chloride and chloride-containing electrolyte. It offers a practical alternative whose potential can be related to the hydrogen-electrode scale.
Platinized platinum : Platinum coated with finely divided platinum to provide a large, catalytically active surface. Its surface adsorbs hydrogen and speeds exchange between hydrogen gas and dissolved hydrogen ions.
Standard electrode potential : The potential of a half-cell measured relative to a reference electrode under standard conditions. The standard hydrogen electrode supplies the zero against which these values are tabulated.
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