Active coefficients, activity

Activity coefficients Activity Index Activol Actuators... 

SPECIFIC ACTIVITY TURNOVER NUMBER OPTICAL ACTIVITY ACTIVITY COEFFICIENT CHEMICAL POTENTIAL FUGACITY LATENT ACTIVITY BIOMINERALIZATION ACTIVITY COEFFICIENT ACTIVITY... 

Table A.2 is model output for seawater freezing at 253.15 K. Beneath the title, the output includes temperature, ionic strength, density of the solution (p), osmotic coefficient amount of unfrozen water, amount of ice, and pressure on the system. Beneath this line are the solution and gaseous species in the system. The seven columns include species identification, initial concentration, final (equilibrium) concentration, activity coefficient, activity, moles in the solution phase, and mass balance. The mass balance column only contains those components for which a mass balance is maintained. The number of these components minus 1 is generally the number of independent components in the system (in this case, 8 — 1 = 7). The mass balances (col. 7) should equal the initial concentrations (col. 2). This mass balance comparison is a good check on the computational accuracy.

EPICS-GC EPICS-GC activity coefficient activity coefficient ... 

Activity coefficient Activity coefficient of the calcium ion Activity coefficient of the carbonate ion Activity coefficient of the hydrogen ion Activity coefficient of the bicarbonate ion Activity coefficient of the hydroxyl ion Ionic strength Mass density of CaC03... 

Millero, F. J., Effects of pressure and temperature on activity coefficients, Activity coefficients in electrolyte solutions, Pytkowicz, R. M., Ed., II, pp.63-I5I, CRC Press, Boca Raton, Florida, (1979). Cited on pages 588, 596. 

Raoult s law, (relative) activity activity coefficient activities and activity coefficients referenced f /b = V B 1... 

The coefficients a,y, and c,y are binary interaction parameters specific to components / and j. A list of binary interaction parameters and Antoine coefficients for systems prominently featured systems in the book are given in Appendix B. Evidently, modeling nonideal systems can be rather laborious and computationally intensive, but the solution strategy is exactly the same to the one outlined for ideal solutions in Equation 1.7, and simply incorporating the activity coefficients. Activity coefficient models can account for azeotropes, that is, where vapor and liquid compositions are equal, while neither Raoult s law nor the constant volatility model is able to. Examples of binary nonideal systems modeled with the NRTL equation are shown in Figure 1.6. 

Total surface strain tensor Phase shift Activity coefficient Electrosorption valency Mean activity coefficient Activity coefficient of an ion... 

In an electric field, the mobility of each ion is reduced because of the attraction or drag exerted by its ionic atmosphere. Similarly, the magnitudes of colligative properties are reduced. This explains why, for example, the value of i for 0.010 m NaCl is 1.94 rather than 2.00. What we can say is that each type of ion in an aqueous solution has two "concentrations." One is called the stoichiometric concentration and is based on the amount of solute dissolved. The other is an "effective" concentration, called the activity, which takes into account interionic attractions. Stoichiometric calculations of the type presented in Chapters 4 and 5 can be made with great accuracy using stoichiometric concentrations. However, no calculations involving solution properties are 100% accurate if stoichiometric concentrations are used. Activities are needed instead. The activity of an ion in solution is related to its stoichiometric concentration through a factor called an activity coefficient. Activities were introduced in Chapter 13. In Chapter 15 their importance in chemical equilibrium will be discussed in more detail. 

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