What is the electrocapillary effect?
The electrocapillary effect is the change in interfacial tension between two immiscible liquids when subjected to an electric field across the interface. The change in interfacial tension occurs due to variations in the surface charge density of adsorbed ions or polar species at the interface.
What is electrocapillary theory?
Electrocapillarity or electrocapillary phenomena are the phenomena related to changes in the surface energy (or interfacial tension) of the dropping mercury electrode (DME), or in principle, any electrode, as the electrode potential changes or the electrolytic solution composition and concentration change.
What are electrocapillary curves?
Electrocapillary curves (surface tension γ as a function of the electrode potential E) for a series of room-temperature ionic liquids (RTILs) were measured using a mercury dropping electrode with the drop-weight (drop-volume) technique. The potential of zero charge is within a relatively narrow range.
Why dropping mercury electrode is used in polarography?
In polarography, mercury is used as a working electrode, because mercury is a liquid metal and thus the electrode can be renewed after each droplet. The working electrode is often a drop suspended from the end of a capillary tube.
What are the advantages of using dropping mercury electrode?
A major advantage of the DME is that each drop has a smooth and uncontaminated surface free from any adsorbed analyte or impurity. The self-renewing electrode does not need to be cleaned or polished like a solid electrode. This advantage comes at the cost of a working electrode with a constantly changing surface area.
What is the effect of concentration of electrolyte on the thickness of electric double layer?
The thickness of the diffuse region of the electric double layer depends on the concentration of ions in the solution: the lower the ion concentration, the thicker the diffuse layer.
What is the advantage of dropping mercury electrode?
What is the principle of dropping mercury electrode?
The principle consisted in weighing drops of mercury falling out of a thick-walled glass capillary into a solution. The dropping mercury, connected to a source of d.c.voltage, served as one electrode, the second electrode being the layer of mercury collecting at the bottom of the vessel.
How does a mercury drop electrode work?
Dropping mercury electrode (DME) is a working electrode arrangement for polarography in which mercury continuously drops from a reservoir through a capillary tube (internal diameter 0.03 – 0.05 mm) into the solution. The optimum interval between drops for most analyses is between 1 and 5 s.
What is the difference between thick double layer and thin double layer?
We find that the thin double layer assumption, in which the thickness of the electrical diffuse layer is assumed small compared to the radius of curvature of a pore or throat, is valid in a capillary tubes model so long as the capillary radius is >200 times the double layer thickness, while the thick double layer …
What is double layer effect?
The formation of double layers is exploited in every electrochemical capacitor to store electrical energy. It is at this interface that the double layer effect occurs. When a voltage is applied to the capacitor, two layers of polarized ions are generated at the electrode interfaces.
What is polarographic technique?
Polarography is a voltammetric technique in which chemical species (ions or molecules) undergo oxidation (lose electrons) or reduction (gain electrons) at the surface of a dropping mercury electrode (DME) at an applied potential.