The Wien effect is the experimentally-observed increase in ionic mobility or conductivity

Conductivity (electrolytic)

The conductivity of an electrolyte solution is a measure of its ability to conduct electricity. The SI unit of conductivity is siemens per meter ....

 of electrolyte

Electrolyte

In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

s at very high gradient of electrical potential. A theoretical explanation has been proposed by Lars Onsager

Lars Onsager

Lars Onsager was a Norwegian-born American physical chemist and theoretical physicist, winner of the 1968 Nobel Prize in Chemistry.He held the Gibbs Professorship of Theoretical Chemistry at Yale University....

.

A related phenomenon is known as the Second Wien Effect or the dissociation field effect, and it involves increased dissociation constant

Dissociation constant

In chemistry, biochemistry, and pharmacology, a dissociation constant is a specific type of equilibrium constant that measures the propensity of a larger object to separate reversibly into smaller components, as when a complex falls apart into its component molecules, or when a salt splits up into...

s of weak acid

Weak acid

A weak acid is an acid that dissociates incompletely. It does not release all of its hydrogens in a solution, donating only a partial amount of its protons to the solution...

s at high electrical gradients. The dissociation of weak chemical bases

Weak base

In chemistry, a weak base is a chemical base that does not ionize fully in an aqueous solution. As Brønsted–Lowry bases are proton acceptors, a weak base may also be defined as a chemical base in which protonation is incomplete. This results in a relatively low pH compared to strong bases...

 is unaffected.

The effects are important at very high electrical gradients (10⁸ - 10⁹ V/m), like those observed in electrical double layers at interfaces

Interface (chemistry)

An interface is a surface forming a common boundary among two different phases, such as an insoluble solid and a liquid, two immiscible liquids or a liquid and an insoluble gas. The importance of the interface depends on which type of system is being treated: the bigger the quotient area/volume,...

 or at the surfaces of electrodes in electrochemistry

Electrochemistry

Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor and an ionic conductor , and which involve electron transfer between the electrode and the electrolyte or species in solution.If a chemical reaction is...

.

More generally, the electric field effect (directly, through space rather than through chemical bonds) on chemical behaviour of systems (e.g., on reaction rate

Reaction rate

The reaction rate or speed of reaction for a reactant or product in a particular reaction is intuitively defined as how fast or slow a reaction takes place...

s) is known as the field effect or the direct effect.

The terms are named after Max Wien

Max Wien

Max Wien was a German physicist and the director of the Institute of Physics at the University of Jena. He was born in Königsberg, Prussia.Wien studied under Helmholtz and Kundt. He invented the "Löschfunkensender" during the years 1906 to 1909 and the Wien bridge in 1891...

.

See also

• Electroviscous effects
  Electroviscous effects
  Electroviscous effects, in chemistry of colloids and surface chemistry, according to an IUPAC definition, are the effects of the particle surface charge on viscosity of a fluid....
  
  
• Field-effect mobility
• Debye length
  Debye length
  In plasma physics, the Debye length , named after the Dutch physicist and physical chemist Peter Debye, is the scale over which mobile charge carriers screen out electric fields in plasmas and other conductors. In other words, the Debye length is the distance over which significant charge...