Ionic activity product

This table gives values of pKw on a molal scale, where Kw is the ionic activity product constant of water. Values are from W. L. Marshall and E. U. Franck, 7. Phys. Chem. Ref. Data, 10 295 (1981). 

Kim, H.-M., Kishimoto, K., Miyaji, F., Kokubo, T., Yao, T., Suetsugu, Y., Tanaka, J. and Nakamura, T. (1999) Composition and structure of the apatite formed on PET substrates in S BF modified with various ionic activity products.Journal of Biomedical Materials Research, 46, 228—235. 

The is called the ionic activity product of water. Replacing activities with concentrations and activity coefficients... 

The ionic activity product of water is very accurately derived, from e.m f. measurement of suitable galvanic cells, such as... 

The authors used Ni and presumably concentrations in the first term on the right hand side of Equation (A.49) but the ionic activity product of H2O in the second term. Thus, adequately corrected numerical values are given in Table V-6 and Figure V-l I. 

In Eq. (3), k is the Boltzmann constant T is the temperature , the saturation state, is defined by fil = lAPIK, where lAP is the ionic activity product of anionic and cationic ions in... 

Ionic activity product Ionic strength Heat flux... 

Solubilities of sulfides in pure water are very low, but they increase significantly in saline and H2S-bearing aqueous solutions. This is due to the stable existence of complexes such as chloro- and thio-complexes. The solubilities of sulfides strongly depend on stability constants of these complexes. Sulfides precipitate when saturation index (S.I.) (S.I. is defined as S.l. = log(I.A.P/Ksp, where I.A.P is activity product and K p is solubility product.) exceeds zero during the flow of ore fluids accompanied by the changes in physico-chemical variables (e.g., decrease of temperature). As an example, precipitation of PbS is considered below. Ionic activity product for PbS (I.A.P) is expressed as... 

Spontaneous precipitation by the mixing of two concentrated solutions of calciiun and carbonate results in a gelatinous matter when ionic activity product exceeds the solubility product of amorphous calcium carbonate. 

In Eqs. (3) and (4), v is the molecular volume, k is the Boltzmann constant, T is the absolute temperature, and S is the supersaturation. For constant temperature and pressure, the supersaturation can be defined as the ratio of ionic activity products. Thus, for a binary electrolyte, S = AP/Xjp, where AP is the ionic activity product in the supersaturated solution and is the solubility product of the respective solute. Equation (3) is known as the Gibbs-Thompson relation, and Eq. (4) was first derived by Gibbs [14] to describe the condensation of droplets from vapor. 

Since at 25°c the value of the ionic activity product of water, is about 10 %. ion /litre, it follows that pliT + pi T = — logA == 14. The lower the value of piiTt, and hence the higher the value of pJiTa the stronger is the base. 

This expression has been written in terms of concentration if activity coefficients sue known or estimated, then a thermodynamically ideal solubility product may be obtained from the Emalogous product of ionic activities. As the concentration of ions in solutions of lanthanide fluorides is low, the concentration and activity solubility products will not differ markedly, although activity coefficients for these salts of 3 + cations are significantly less than unity even in such dilute solutions (4a). 

It appeared to us that the only reasonable non-ionic reaction product of an acid and an olefin would be an ester, and for this reason we put forward the idea that this is the active species in the pseudo-cationic polymerizations. Of course, the idea of an ester in this role has a respectable ancestry which has been discussed in this new context [6]. The ester mechanism of polymerization will be discussed in sub-section 3.3. It must be understood that our conclusion concerning the non-ionic nature of the chain-carriers in the pseudocationic polymerizations is quite independent of our view that the chain-carriers are esters this is at present merely an hypothesis to explain our factual conclusion. 

Once the composition of the aqueous solution phase has been determined, the activity of an electrolyte having the same chemical formula as the assumed precipitate can be calculated (11,12). This calculation may utilize either mean ionic activity coefficients and total concentrations of the ions in the electrolyte, or single-ion activity coefficients and free-species concentrations of the ions in the electrolyte (11). If the latter approach is used, the computed electrolyte activity is termed an ion-activity product (12). Regardless of which approach is adopted, the calculated electrolyte activity is compared to the solubility product constant of the assumed precipitate as a test for the existence of the solid phase. If the calculated ion-activity product is smaller than the candidate solubility product constant, the corresponding solid phase is concluded not to have formed in the time period of the solubility measurements. Ihis judgment must be tempered, of course, in light of the precision with which both electrolyte activities and solubility product constants can be determined (12). 

So far, we have expressed the number of ions per unit volume by concentration. Physical chemists prefer to use activity to characterize the behavior of solutes in solution. As a solution becomes more concentrated and as the ionic strength increases, ions behave as if there were fewer of them present than would be indicated by their analytical concentrations. The activity of a component is related to its concentration by a proportionality constant known as an activity coefficient . Considerations regarding ionic activity become particularly important, when fluids are quite concentrated. An extension of this treatment is the use of the activity product to... 

The following factors appear to control the emulsification properties of milk proteins in food product applications 1) the physico-chemical state of the proteins as influenced by pH, Ca and other polyvalent ions, denaturation, aggregation, enzyme modification, and conditions used to produce the emulsion 2) composition and processing conditions with respect to lipid-protein ratio, chemical emulsifiers, physical state of the fat phase, ionic activities, pH, and viscosity of the dispersion phase surrounding the fat globules and 3) the sequence and process for incorporating the respective components of the emulsion and for forming the emulsion. 

This expression describes what is known as the Donnan equilibrium. It does not say that the activity of M+ and/or X is the same on both sides of the membrane, but that the ion activity product is constant on both sides of the membrane. In the sense that an ion product is involved, the Donnan equilibrium clearly resembles all other ionic equilibria. 

Our procedure was to follow the changes in concentrations and ionic strength as the water is evaporated, and by correcting ion molalities by activity coefficients, keep track of the ion activity products of the various... 

The logarithm of the quotient of the ion activity product (IAP) and solubility product constant (KSP) is called the saturation index (SI). The IAP is calculated from activities that are calculated from analytically determined concentrations by considering the ionic strength, the temperature, and complex formation. The solubility product is derived in a similar manner as the IAP but using equilibrium solubility data corrected to the appropriate water temperature. 

Ion activity product, 48-53 Ionic potential, 287 Ionic strength, 45 Ion pairing, 53 Iron, 289-290... 

Ysvi ln ai refers to the cell reaction, with vf positive for products and negative for reactants for the complete cell reaction only mean ionic activities a are involved. 

We recognize that z < 0 hence, we have introduced the absolute value, z. Second, there is no possibility of separately determining either a+ or a. For, by definition, /i+ (3G/dn+)T p n that is, the determination of /i+ requires addition of just positive ions to the solution, while holding the concentration of anions fixed. However, this step cannot be carried out operationally because it involves a violation of the Law of Electroneutrality. Consequently, one should not attempt to deal with individual ionic activities rather, as Eq. (4.1.3b) shows, the ionic activities occur in such a manner that only their product or their logarithmic sum is involved. Third, since thermodynamic descriptions must be confined to measurable properties we may regard the quantity n + RT in a on the left of Eq. (4.1.3a) as an effective chemical potential that is to be used to represent the behavior of the electrolytes. On the other hand, one does not wish to ignore the ionic nature of the solution hence it is customary to set... 

What is the significance of these quantities fi, x, and It is obvious they are all average quantities—the mean chemical potential the mean standard chemical potential the mean ionic mole fraction x, and the mean ionic-activity coefficient f. In the case of and fi% the arithmetic mean (half the sum) is taken because free energies are additive, but in the case of x and f , the geometric mean (the square root of the product) is taken because the effects of mole fraction and activity coefficient on free energy are multiplicative. 

The equilibrium between H3O+ and OH ions will exist in pure water and in all aqueous solutions if the ionic strength of the medium is low, the ionic activity coefficients may be taken as unity, and hence the ionic product of water, now represented by is given by... 

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