Ionic strength molar

A.V. (1997) Adsorption of a corticoid on colloidal hematite particles of different geometries. J. Colloid Interface Sd. 187 429-434 Verdonck, L. Hoste, S. Roelandt, F.F. Van der Kelen, G.P. (1982) Normal coordinate analysis of a-FeOOH - a molecular approach. J. Molecular Structure 79 273-279 Vermilyea, D.A. (1966) The dissolution of ionic compounds in aqueous media. J. Electro-chem. Soc. 113 1067-1070 Vermohlen, K. Lewandowski, H. Narres, H-D. Schwager, M.S. (2000) Adsorption of polyelectrolytes onto oxides - the influence of ionic strength, molar mass and Ca " ions. Coll. Surf. A 163 45-53... 

FIGURE 6.11 Viscosity parameters of solutions of carboxymcthyl cellulose (Na salt) at various ionic strengths (molar). Mark-Houwink parameters K (ml/g) and a, and intrinsic viscosity [>y]0(ml/g) for a molar mass of 106Da. (From results by W. Brown and D. Henley. Makromol. Chemie 79 (1964) 68.)... 

Hedstrom number ionic strength (molar) constant... 

Figure 9.5. Logarithm of experimentally determined stability ratios for colloidal silica ca = 6 X 10 clusters/ m ) as a function of the logarithm of the ionic strength (/= molarity of KCI) contoured in aggregate size expressed as the number (N) of 12 nm diameter unit clusters in the aggregate (pH = 9,4)(Axford, 1997).

At high ionic strength the electrostatic contributions are screened. Therefore, the chemical interactions become important. Very high adsorption may be observed if the solvent is very poor for the polyelectrolyte under these conditions. At high ionic strength molar mass effects are important. 

Tj = temperature, °F p = pressure, psia I = ionic strength, molar T = temperature, K... 

The ionic strength can be estimated from the summation of the product molarity times ionic charge squared for all the ionic species present in the solution, i.e., I = 0.5(ciZi + C2Zi + + qzf). 

Note that the unit for ionic strength is molarity, but that the molar ionic strength need not match the molar concentration of the electrolyte. For a 1 1 electrolyte, such as NaCl, ionic strength and molar concentration are identical. The ionic strength of a 2 1 electrolyte, such as Na2S04, is three times larger than the electrolyte s molar concentration. 

In many situations, the actual molar amount of the enzyme is not known. However, its amount can be expressed in terms of the activity observed. The International Commission on Enzymes defines One International Unit of enzyme as the amount that catalyzes the formation of one micromole of product in one minute. (Because enzymes are very sensitive to factors such as pH, temperature, and ionic strength, the conditions of assay must be specified.) Another definition for units of enzyme activity is the katal. One katal is that amount of enzyme catalyzing the conversion of one mole of substrate to product in one second. Thus, one katal equals 6X10 international units. 

In accordance with Eq. (3.4) or Eq. (3.6), the concentration selectivity of ion exchange is variable depending on the degree of ideality of the solution and CP phase. For dilute solutions at a constant ionic strength, it is possible to take into account as a variable only the degree of non-ideality of the CP phase. For the systems considered here, it is convenient to study the effect of the molar fraction of organic counterions (NJ on the concentration selectivity constant. Fig. 14 shows the dependences of Ks on the molar fraction of oxytetracycline in CP. For CP... 

In equation (i )[Na ] is the total molar concentration of free sodiiam ions, [ SL j is the molar concentration of ionic Cj 2 25 S05J, and [SLS]jjj is the concentration of the SLS micelles. The corresponding ionic strengths are indicated in the fig ire heading. The capillary model can also be used to account for the ionic strength effects seen in Figure 2 and is discussed elsewhere (23). 

Molar concentrations in millimoles (quantities in parentheses are total ionic strengths calculated from Equation 4), (O) 0.22mM 0.55mM SLS (V) l.OSmM SLS (0 )... 

Lewis and Randall stated that in dilute solutions the activity coefficient of a strong electrolyte is the same in all solutions of the same ionic strength this statement was confirmed in thermodynamic deductions of activity coefficients. The molality version of 7 can be applied in a fully analogous way and allows a more straightforward treatment of solution properties. [Conversion of molality into molarity requires the solution densities e.g., for a solute of molar mass M and a solution of density q we have... 

The complexing behavior of Ca2+ is put into context in Table VI (49,208,211,236-246), which provides a comparison of stability constants (logioifi, on the molar scale, in aqueous media at 298 K (a few at 293 K), generally at 7 0.1M) for a selection of complexes of Ca2+ with those for a range of other metal cations. Ionic strength effects are often significant, especially for ionic... 

Fig. 2. Overview of stability constants (logio-Ka, on the molar scale) for formation of calcium complexes in aqueous solution, at (or close to) 298 K and in ionic strengths in the region of 0.1-0.15 M.

Activity coefficient vary with the concentration especially in the presence of added electrolyte. Lewis and Randall introduced the quantity called ionic strength which is a measure of the intensity of the electric field due to the ions in a solution. It is defined as the sum of the terms obtained by multiplying the molarity (concentration) of each ion present in solution by the square of its valence... 

The electrophoretic mobility of an ion is inversely related to the ionic strength of the buffer rather than to its molar concentration. The ionic strength (ytt) of a buffer is half the sum of the product of the molar concentration and the valency squared for all the ions present in the solution. The factor of a half is necessary because only half of the total ions present in the buffer carry an opposite charge to the colloid and are capable of modifying its charge ... 

These equilibrium constants vary with molarity of the HF solution. Measured values corrected for zero ionic strength at 25 °C are = 6.71 x 10 4 mol 1, K2=3.86 1 mol-1, and K3=2.71mor1 [BrlO, Iul, Wall], implying a dissociation of only a few percent. This unusual behavior is still controversial and has been attributed to the greater strength of the H-F bond compared to the other hydrogen halides [Pal], to the presence of the dimer (HF)2 [Wal], or to polymers that may... 

---