Charge-balancing counter-ions

Figure 6.16 The structure of Prussian Blue. The charge balancing counter-ions are located at the centers of the cubes within the structure. Movement of ions in and out of the structure is limited by the size of the pores in the faces of the cube.

Coordination compounds consist of a complex ion and charge-balancing counter ions. The complex ion has a central metal ion bonded to neutral and/or anionic ligands, which have one or more donor atoms that each have a lone pair of electrons. 

Fig. 3 The p-doped PEDOT stmcture. The oxidant A served as the charge balancing counter-ion to the PEDOT during polymerization...

For microgel particles having a bulk charge there is an additional osmotic contribution from the charge-balancing counter-ions within the microgel particles [5]. In the simplest case, where the counter-ions may be treated ideally, one may write [4] this additional (ionic) contribution to the osmotic term as ... 

Also used to describe the oppositely charged ion balancing charge, e.g. chloride is the counter-ion to Na in sodium chloride. 

Fig. 19.39 Schematic representation of reactions during (a) controlled potential and (b) conventional corrosion tests in acidic chloride solutions. In (a) charge balance must be maintained by migration of Cl" ions, since the cathodic reaction occurs elsewhere at the counter-electrode. In (b) the anodic and cathodic sites are in close proximity, and charge balance is maintained without migration of Cl" ions from the bulk solution (after France and Greene )...

Helgeson, Tarnowski Cram, 1979). X-ray diffraction confirms that a similar structure occurs in the solid state in this instance, the tetra-methylene diammonium ion is the guest (the dipositive charge on the complex is balanced by a pair of uncoordinated hexafluorophosphate counter ions) (Goldberg, 1977). 

Ion pairs are outer-sphere association complexes, which have to be clearly distinguished from the organometallic complexes discussed in Section 6. Ion pair formation appears to be much less important in biological membranes as compared with octanol, because the charge of the ions at the membrane interphase can be balanced by counter charge in the electrolyte in the adjacent aqueous phase. The reactions involved in ion pair formation are depicted in Figures 5b for acids and 5c for bases, and the equilibrium constant K ix is defined as follows ... 

Simple electrolyte ions like Cl, Na+, SO , Mg2+ and Ca2+ destabilize the iron(Hl) oxide colloids by compressing the electric double layer, i.e., by balancing the surface charge of the hematite with "counter ions" in the diffuse part of the double... 

Clay minerals have a permanent negative charge due to isomorphous substitutions or vacancies in their structure. This charge can vary from zero to >200cmol kg" (centimoles/kg) and must be balanced by cations (counter-ions) at or near the mineral surface (Table 5.1), which greatly affect the interfacial properties. Low counter-ion charge, low electrolyte concentration, or high dielectric constant of the solvent lead to an increase in interparticle electrostatic repulsion forces, which in turn stabilize colloidal suspensions. An opposite situation supports interparticle... 

At the copper electrode, reduction of Cu2+ is favoured and oxidation of Cu atoms is restricted, so that net cathodic flow occurs. Finally, to prevent a build up of Zn2+ ions near the zinc/electrolyte interface and of SO42-counter ions near the copper, a flux of ions must take place in the electrolytic phase to balance the charge transfer processes at the interfaces. To maintain the flux continuity condition, the applied voltage difference becomes distributed in such a way that ... 

Ions in solution adsorb at mineral/solution interfaces to balance the surface charge and maintain electroneutrality. These ions are known as the counter ions. In contrast to the situation... 

Counter ion — A mobile ion that balances the charge of another charged entity in a solution. It is a charged particle, whose charge is opposite to that of another electrically charged entity (an atom, molecule, micelle, or surface) in question [i]. Counter ions can form electrostatically bound clouds in the proximity of ionic macromolecules and in many cases, determine their electric properties in solution [ii]. 

---