Effects of other ions

In SI units, E is expressed in volt meter -1 and q in coulombs, so Fel is correctly given in newtons, since C V = J = N m. The cgs unit system, which is widely encountered in older references, requires dividing the right-hand side of Equation (1) by a factor of about 300 since 299.8 V = 1.0 statvolt. Use of Equation (1) is limited to situations in which the electric field at the ion is due to the applied potential gradient only, undisturbed by the effects of other ions in the solution (i.e., infinite dilution). 

This value is comparable to those for the luminescent ion chemosensor systems based on fibre optics or flow-through measurements. In general, the effect of other ions on MIP may be assumed to be negligible, as confirmed by the low MIP fluorescence measured during cross-reactivity tests. However, in toluene in the presence of Mg2+ the MIP fluorescence increased significantly ( 50% of the total intensity) as compared to that in the presence of Al3+. Moreover, Be2+ in ACN yielded almost equal response (90%) to that measured in the presence of Al3+. 

The data indicate that, at a pH of 2, divalent Mn and Fe have much lower conditional stability constants than Sc, and therefore Sc would be complexed preferentially, even in the presence of larger concentrations of these ions. However, the Kml- of die ferric ion is larger than that of Sc, and it is thus mandatory to keep all iron in the solution in the ferrous state in order to achieve selective Sc complexation and, if this model is reasonable, selective retention on the ion exchange column. The data for Th and Ca are presented to illustrate the effect of other ions Ca presents no problem as it is not complexed at this pH with EDTA, while Th would be coextracted at a comparable rate with Sc. The assumptions of this model have been proven valid, as shown by the data below (Table VI) which demonstrate the selective extraction of Sc on the ion exchange column with iminodiacetic acid functionality in the presence of a large excess of Mn and Fe. 

The acidity of the medium has an important influence on the form of certain ions in the solution e.g., Zr, Ti, V) and this form is decisive for the kind of reaction (in the ease of Zr Zr" ", ZrO ", polymerized forms). In the reactions of chemical species with some reagents, the optimum pH range may be narrow, either because of the maximum sensitivity of the colour reaction or the effect of other ions. 

Effects of other ions in solution on the acid-base reactions are accounted for in two complementary ways - via activity coefficients in the equilibrium equations ( 3) ... 

Not all salts exhibit a good aqueous solubility. A number of inorganic salts having a relatively low molecular weight and a low water solubility are listed in Table 18.6. Also the solubility product often is given (Table 18.7). This allows us to determine the effect of other ions in the solution on the solubility of a given substance, for example, when sodium carbonate is added to a solution of magnesium chloride. Also the reduction of the solubility of the poorly soluble calcium carbonate can be calculated when a certain amount of the readily soluble sodium carbonate or calcium chloride is added. This reduction in the solubility of, in this case, calcium carbonate is also known as the common ion effect. 

An electrolyte contains a very low activity (8 10 mol/l) of silver cations Ag+) and an unknown concentration of copper cations. If the cell potential difference between the copper anode and the silver cathode is -0.04 V, determine a) which cation will be reduced (electroplated) on the cathode and b) the concentration of [Cu+ ] in g/l at 40°C. Neglect the effects of other ions that might react with silver. [Solution a) Ag will be reduced and b) [Cu+2] = 60.19 g/l]. 

In all natural sea waters with a salinity exceeding about 10%o, the total alkalinity will arise from the ions COg , HCOg, HgBOg ", OH and, in a negative sense, H+. The effect of other ions can be neglected. Therefore, by definitions, if [ ] represents concentration in millimoles per liter. 

When using an ammonia sensitive electrode, care should be taken in handling and storage as well as the effect of other ions in solution. 

Increased A1 mobility due to complexing by organic acids is unlikely in natural pore waters due to the competing effects of other ions for the organic acid ligands. 

The screening effect of other ions is neglected, as g is considered to be small. Let I be that part of the statistical mechanical phase integral which corresponds to the region close to the line charge ... 

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