Electrocapillarity or Electrocapillary phenomena are the phenomena related to changes in the surface energy (or interfacial tension) of the Dropping mercury electrode

Dropping mercury electrode

The dropping mercury electrode is a working electrode made of mercury and used in polarography. Experiments run with mercury electrodes are referred to as forms of polarography even if the experiments are identical or very similar to a corresponding voltammetry experiment which use solid working...

 (DME) as the electrode potential

Electrode potential

Electrode potential, E, in electrochemistry, according to an IUPAC definition, is the electromotive force of a cell built of two electrodes:* on the left-hand side is the standard hydrogen electrode, and...

 changes or the electrolytic solution

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....

 composition and concentration change. The term "Electro-Capillary" is used to describe the change in mercury

Mercury (element)

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

 (Hg) electrode

Electrode

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...

 potential as a function of the change in the surface or interfacial tension of the Hg determined by the capillary rise

Capillary action

Capillary action, or capilarity, is the ability of a liquid to flow against gravity where liquid spontanously rise in a narrow space such as between the hair of a paint-brush, in a thin tube, or in porous material such as paper or in some non-porous material such as liquified carbon fiber, or in a...

  method. The phenomena are the historic main contributions for understanding and validating the models of the structure of the electrical double layer. The phenomena are related to the electrokinetic phenomena and consequently to the colloid

Colloid

A colloid is a substance microscopically dispersed evenly throughout another substance.A colloidal system consists of two separate phases: a dispersed phase and a continuous phase . A colloidal system may be solid, liquid, or gaseous.Many familiar substances are colloids, as shown in the chart below...

 chemistry.

Interfacial tension

The interfacial (surface) tension, St, (dyne cm⁻¹), can be calculated by applying the equation of capillary rise method (when the contact angle Ө → 0):

St = ½ h r g d

where:

• h (cm) is the height of Hg column above the Hg meniscus
  Meniscus
  The meniscus is the curve in the upper surface of a liquid close to the surface of the container or another object, caused by surface tension. It can be either convex or concave. A convex meniscus occurs when the molecules have a stronger attraction to each other than to the material of the...
  
   in the capillary
• r (cm) is the radius
  RADIUS
  Remote Authentication Dial In User Service is a networking protocol that provides centralized Authentication, Authorization, and Accounting management for computers to connect and use a network service...
  
   of capillary
• d (g cm⁻³) is the Hg density
  Density
  The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
  
  
• g is the acceleration
  Acceleration
  In physics, acceleration is the rate of change of velocity with time. In one dimension, acceleration is the rate at which something speeds up or slows down. However, since velocity is a vector, acceleration describes the rate of change of both the magnitude and the direction of velocity. ...
  
   due to gravity, g = 981 cm s⁻².

The circuit contains Hg electrode as the ideally polarizable electrode and a reference electrode

Reference electrode

A reference electrode is an electrode which has a stable and well-known electrode potential. The high stability of the electrode potential is usually reached by employing a redox system with constant concentrations of each participants of the redox reaction.There are many ways reference...

 as the non-polarizable electrode. Thus, when an external voltage is applied, only EM/S of Hg/solution interface is changed.

See also

• Electrical double layer
• Electrokinetic phenomena
  Electrokinetic phenomena
  Electrokinetic phenomena are a family of several different effects that occur in heterogeneous fluids or in porous bodies filled with fluid. The term heterogeneous here means a fluid containing particles...
  
  
• Colloid chemistry
• Liquid metal electrode
  Liquid metal electrode
  Liquid metal electrode is a replacement for mercury electrode variants. A few examples are those based on galinstan, NaK. They can be used in the same way as the mercury electrode in electrocapillarity, voltametry, impedance measurement.-External links:**...