Generalized equilibrium-constant expression

The general equilibrium constant expression in equation (2.2) can be rewritten to express the distribution of solute chemical X between water (W) and K-octanol (O) as... 

Physical Equilibrium Chemical Equilibrium The Generalized Equilibrium-Constant Expression for a Chemical Reaction LeChateller s Principle Summary Key Terms... 

The Generalized Equilibrium-Constant Expression for a Chemical Reaction... 

Now, according to the generalized equilibrium constant expression (15.7), we should write... 

For every gaseous chemical system, an equilibrium constant expression can be written stating the condition that must be attained at equilibrium. For the general system involving only... 

The equilibrium constant expression given by Equation is completely general and can be applied to any chemical reaction. Three features of equilibrium constants are especially important ... 

Chemical equilibria often involve pure liquids and solids in addition to gases and solutes. The concentration of a pure liquid or solid does not vary significantly. Figure 16-4 shows that although the amount of a solid or liquid can vary, the number of moles per unit volume remains fixed. In other words, the concentrations of pure liquids or solids are always equal to their standard concentrations. Thus, division by standard concentration results in a value of 1 for any pure liquid or solid. This allows us to omit pure liquids and solids from equilibrium constant expressions. For a general reaction (2A + iBt= C D-l-. S where S is a pure solid or liquid ... 

Examine each reaction closely, and look for the characteristic features of the general equilibria. The equilibrium constant expression can be written by inspecting the overall stoichiometry. 

The equilibrium constant expression derived for calcium carbonate dissolving in acidic solution is a general one... 

Because the two equilibrium constant expressions have similar magnitudes, a solution of the silver-ammonia complex generally has a significant concentration of each of the species that participate in the equilibria. The details of such calculations are beyond the scope of general chemistry. When the solution contains a large excess of ligand, however, each step in the complexation process proceeds nearly to completion. Under these conditions we can apply the standard seven-step approach to a single expression that describes the formation reaction of the complete complex. 

Next we must check whether our approximation was valid. Is it true that 1.50 - 0.058 a 1.50 and 2.25 - 0.058 = 2.25 Considering the limits of accuracy of the equilibrium constant expression, results within 5% accuracy are considered valid for the general chemistry course. These results are thus valid. The equilibrium concentrations are... 

When the drug entity is capable of forming complexes that have higher stoichiometric ratios than 1 1, the construction of equilibrium constant expressions becomes more difficult. For the general case of m.n stoichiometry, as defined by... 

It is to be noticed that both of these equilibrium constants are protonation constants, since they apply to the addition of a proton (H+) to a given species. The pH values for which these reactions occur can be determined using equilibrium constant expressions and the appropriate equilibrium constant, K. Recall that equilibrium expressions take the general form of ... 

Values of Kc are generally reported without units because the concentrations in the equilibrium constant expression are considered to be concentration ratios in which the molarity of each substance is divided by its molarity (1 M) in the thermodynamic standard state (Section 8.6). Because the units cancel, the concentration ratios and the values of Kc are dimensionless. For experiment 1 in Table 13.1, for example,... 

As K is independent of pressure, Pg / PA (= K) should also be independent of pressure. However, the compression, or pressure change in general, adjusts the individual partial pressures of the species in such a way that, although the partial pressure of each species changes, their ratio appearing in the equilibrium constant expression remains unchanged. 

Figure A.l. summarises the various forms of writing various equilibrium constant expressions Kp/po, Kc/co, Km/mo, Kf/po and Kx for a general reaction of the form of (A. 12) in the cases ...

Quantitative calculations can be made for systems at equilibrium using the equilibrium constant expression. For the general reaction... 

Law of definite proportion a given compound always contains exactly the same proportion of elements by mass. (2.2) Law of mass action a general description of the equilibrium condition it defines the equilibrium constant expression. (6.2) Law of multiple proportions when two elements form a series of compounds, the ratios of the masses of the second element that combine with one gram of the first element can always be reduced to small whole numbers. (2.2)... 

You are given a heterogeneous equilibrium involving gases and solids. The general form of the equilibrium constant expression for this reaction is... 

Equation 9-7 is only an approximate form of a thermodynamic equilibrium constant expression. The exact form is given by Equation 9-8 (in the margin). Generally, we use the approximate form of this equation because it is less tedious and time consuming. In Section lOB, we show when the use of Equation 9-7 is likely to lead to serious errors in equilibrium calculations and how Equation 9-8 is modified in these cases. 

Describe three general methods for performing EDTA titrations. What are the advantages of each 17-3. Why are multidentate ligands preferable to unidentate ligands for complexometric titrations 17-4. Write chemical equations and equilibrium-constant expressions for the stepwise formation of (a) Ni(CN)5-. 

Even if the overall reaction occurs by a multistep mechanism, we can show that the equilibrium constant is the product and ratio of the rate constants for each step of the mechanism. Regardless of the mechanism by which this reaction occms, the concentrations of reaction intermediates cancel out and the equilibrium constant expression has the same form. For a reaction in general terms, the equilibrium constant can always be written as follows ... 

In general, numerical values for K. can come only from experiments. Some equilibrium constant expressions and their numerical values at 25°C are... 

In general we find K = Kq x The remaining reactions and their equilibrium constant expressions are ... 

The Henderson-Hasselbalch equation was developed independently by the Ameriean biological chemist L. J. Henderson and the Swedish physiologist K. A. Hasselbaleh, for relating the pH to the bicarbonate buffer system of the blood (see below). In its general form, the Henderson-Hasselbalch equation is a useful expression for buffer caleulations. It can be derived from the equilibrium constant expression for a dissociation reaction of the general weak acid (HA) in Equation (1.3) ... 

Substances whose concentrations undergo no significant change in a chemical reaction do not appear in equilibrium constant expressions. How can the concentration of a reactant or product not change when a reaction involving that substance takes place There are two general cases to consider. 

The extent to which reversible reactions proceed toward products before reaching equilibrium can be described with an equilibrium constant, which is derived from the ratio of the concentrations of products to the concentrations of reactants at equilibrium. For homogeneous equilibria, the concentrations of all reactants and products can be described in moles per liter, and the concentration of each is raised to a power equal to its coefficient in a balanced equation for the reaction. The following shows the general form for the equilibrium constant expression ... 

Note Although all three species must be present at equilibrium, the equilibrium constant expression does not include a term for the solid Ag2S04. This is in keeping with the general statement that the algebraic form of K can be deduced from the stoichiometric equation, with the proviso that there are no terms for any pure solid, pure liquid or solvent. As mentioned previously, that this is so becomes abundantly clear when the algebraic form is deduced from the thermodynamic argument. This will be explained in Sections 8.13 and 8.14. 

The equilibrium constant expression for a general equilibrium reaction... 

Although an absolute interpretation of the numerical value of the equilibrium constant depends on the form of the equilibrium-constant expression, the following generalizations are useful ... 

State the general form of the equilibrium constant expression. 

Law of mass action a general description of the equilibrium condition it defines the equilibrium constant expression. (6.2)... 

When the reactants and products in a chemical reaction are gases, we can formulate the equilibrium-constant expression in terms of partial pressures. When partial pressures in atmospheres are used in the expression, we denote the equilibrium constant Kp (where the subscript p stands for pressure). For the general reaction in Equation 15.7, we have... 

For the equilibrium constant to be so large, the numerator of the equilibrium-constant expression must be approximately a billion (10 ) times larger than the denominator. Thus, the equilibrium concentration of COCI2 must be much greater than that of CO or CI2, and in fact this is just what we find experimentally. We say that this equilibrium lies to the right (that is, toward the product side). Likewise, a very small equilibrium constant indicates that the equilibrium mixture contains mostly reactants. We then say that the equilibrium lies to the left. In general,... 

This approach can be formalized by defining a quantity called the reaction quotient. The reaction quotient, Q, is a number obtained by substituting reactant and product concentrations or partial pressures at any point during a reaction into an equilibrium-constant expression. Therefore, for the general reaction... 

The equilibrium-constant expression for a general reaction of the type a A + bB concentrations are equilibrium concentrations only... 

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