Aqueous Solutions and Chemical Equilibria

Chapter 9 Aqueous Solutions and Chemical Equilibria 228 Chapter 10 Effect of Electrolytes on Chemical Equilibria 267 Chapter 11 Solving Equilibrium Calculations for Complex Systems 281... 

While both NMR and infrared spectra can be used to study aqueous solutions and chemical equilibria, it is probably easier to measure such ionic species as with an NMR spectrometer. 

Source Values are compiled from the following sources Bard, A. J. Parsons, R. Jordon, J., eds. Standard Potentials in Aqueous Solutions. Dekker New York, 1985 Milazzo, G. Carol , S. Sharma, V. K. Tables of Standard Electrode Potentials. Wiley London, 1978 Swift, E. H. Butler, E. A. Quantitative Measurements and Chemical Equilibria. Freeman New York, 1972. 

This interaction between physical and chemical equilibria complicates considerably the description of vapor-liquid equilibria in multicomponent aqueous solutions. The development of thermodynamic correlations for those equilibria is also hindered by the limited experimental material available on that subject. 

Information on the speciation states of solutes and their equilibria with condensed phases furnished by Eh-pH diagrams is often simply qualitative and should be used only in the initial stages of investigations. The chemical complexity of natural aqueous solutions and the persistent metastability and redox disequilibrium induced by organic activity are often obstacles to rigorous interpretation of aqueous equilibria. 

Other portions of weathering profiles will establish, at any given point, an equilibrium between the fluid or aqueous solution and the silicate-oxide solids in the soil. Each portion of the profile will represent a different series of chemical conditions, i.e., the total relative masses of the various components will change with, for example, K O increasing downwards in the profile. However, the phase equilibria are such that the different portions of the profile can be analyzed on a P constant, T constant, X diagram for any small segment of the profile. 

The law of mass action is widely applicable. It correctly describes the equilibrium behavior of all chemical reaction systems whether they occur in solution or in the gas phase. Although, as we will see later, corrections for nonideal behavior must be applied in certain cases, such as for concentrated aqueous solutions and for gases at high pressures, the law of mass action provides a remarkably accurate description of all types of chemical equilibria. For example, consider again the ammonia synthesis reaction. At 500°C the value of K for this reaction is 6.0 X 10 2 F2/mol2. Whenever N2, H2, and NH3 are mixed together at this temperature, the system will always come to an equilibrium position such that... 

The general principles of chemical equilibrium apply equally to reactions of neutral molecules and to reactions of ions. Because of the special interest which chemists have in ionic equilibria in aqueous solutions and because of some common methods of treating some of these problems, this chapter and the following are devoted to the specific applications of chemical equilibrium to ionic reactions. As in Chapter 16, concentrations will always be expressed in mol/L, and [X] will represent the numerical value of the concentration of X. 

In this chapter we will consider some additional fundamental aspects of chemical reactions, i.e., how they occur, the driving forces behind them, and their dependence upon specifics of molecular structure and conditions of reaction, such as temperature and concentration. There are two aspects of chemical reactions which, though interrelated, are dealt with as separate topics. The first of these is the study of the reaction from its initiation to the point where the system seems to undergo no further change, called chemical kinetics. The second deals with the system after all apparent change has stopped, and is called chemical equilibrium. Following those topics we will examine some specific aspects of chemical equilibria involving oxidation-reduction reactions in aqueous solutions and combustion reactions. 

Both reaction kinetics and chemical equilibria of the formation/decomposition of 1,3,5-trioxane in aqueous formaldehyde solutions were studied by quantitative H NMR spectroscopy <2006MI910> a virtual reference signal of high stability was generated electronically and employed for the quantification of the small 1,3,5-trioxane proton signal. 

Chapter 1 provides an extensive discussion of chemical equilibria as they pertain to minerals. This covers in detail chemical equilibria of solids and aqueous solutions, the solubility of various types of minerals, the weathering of silicate and aluminosilicate minerals, the composition of geothermal and groimd water, hydro-thermal alteration, oxidation and reduction reactions, and the partitioning of elements between aqueous solutions and crystals. 

Wolery TJ (1979) Calculation of chemical equilibria between aqueous solutions and minerals the EQ3/6 software package. Lawrence Livermore National Laboratory Rep. UCRL-52658, 41 pp... 

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