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In coordination chemistry, a stability constant (also called formation constant or binding constant) is an equilibrium constant for the formation of a complex in solution. It is a measure of the strength of the interaction between the reagents that come together to form the complex. There are two main kinds of complex: compounds formed by the ...
In chemistry, ion association is a chemical reaction whereby ions of opposite electric charge come together in solution to form a distinct chemical entity. [1] [2] Ion associates are classified, according to the number of ions that associate with each other, as ion pairs, ion triplets, etc. Ion pairs are also classified according to the nature of the interaction as contact, solvent-shared or ...
Thiocyanate complexes are not widely used commercially. Possibly the oldest application of thiocyanate complexes was the use of thiocyanate as a test for ferric ions in aqueous solution. [15] The reverse was also used: testing for the presence of thiocyanate by the addition of ferric salts. The 1:1 complex of thiocyanate and iron is deeply red.
Lesser amounts of other hydrated compounds also form: e.g. Fe(SCN) 3 and [Fe(SCN) 4] −. [19] Similarly, Co 2+ gives a blue complex with thiocyanate. [20] Both the iron and cobalt complexes can be extracted into organic solvents like diethyl ether or amyl alcohol. This allows the determination of these ions even in strongly coloured solutions.
The role of water in the association equilibrium is ignored as in all but the most concentrated solutions the activity of water is constant. K is defined here as an association constant, the reciprocal of an acid dissociation constant. Each activity term { } can be expressed as the product of a concentration [ ] and an activity coefficient γ ...
However, the equilibrium constant for the loss of two protons applies equally well to the equilibrium [M(H 2 O) n] z+ - 2 H + ⇌ [MO(H 2 O) n-2] (z-2)+ + H 2 O. because the concentration of water is assumed to be constant. This applies in general: any equilibrium constant is equally valid for a product with an oxide ion as for the product with ...
The value of the equilibrium constant for the formation of a 1:1 complex, such as a host-guest species, may be calculated with a dedicated spreadsheet application, Bindfit: [4] In this case step 2 can be performed with a non-iterative procedure and the pre-programmed routine Solver can be used for step 3.
An attempt to quantify the 'softness' of a base consists in determining the equilibrium constant for the following equilibrium: BH + CH 3 Hg + ⇌ H + + CH 3 HgB. where CH 3 Hg + (methylmercury ion) is a very soft acid and H + (proton) is a hard acid, which compete for B (the base to be classified). Some examples illustrating the effectiveness ...