Equilibrium expressions for

Substituting for [PhCOCH2 ] from the equilibrium expression for step 1 gives... 

Many organic reactions involve acid concentrations considerably higher than can be accurately measured on the pH scale, which applies to relatively dilute aqueous solutions. It is not difficult to prepare solutions in which the formal proton concentration is 10 M or more, but these formal concentrations are not a suitable measure of the activity of protons in such solutions. For this reason, it has been necessaiy to develop acidity functions to measure the proton-donating strength of concentrated acidic solutions. The activity of the hydrogen ion (solvated proton) can be related to the extent of protonation of a series of bases by the equilibrium expression for the protonation reaction. 

Derive an equilibrium expression for the reactive absorption of HiS in diethanolamine DEA . The molarity of DEA is 2 kmol/m. The following reaction takes place ... 

The problem can be solved using the equilibrium expression for the adenylate kinase reaction ... 

This equilibrium constant is often given the symbol Kp to emphasize that it involves partial pressures. Other equilibrium expressions for gases are sometimes used, including Kc ... 

The above rate equation is in agreement with that reported by Madhav and Ching [3]. Tliis rapid equilibrium treatment is a simple approach that allows the transformations of all complexes in terms of [E, [5], Kls and Kjp, which only deal with equilibrium expressions for the binding of the substrate to the enzyme. In the absence of inhibition, the enzyme kinetics are reduced to the simplest Michaelis-Menten model, as shown in Figure 5.21. The rate equation for the Michaelis-Menten model is given in ordinary textbooks and is as follows 11... 

A proponent of "reverse weathering" suggested that gibbsite, kaolinite, and quartz exist in equilibrium according to the following equation. In equilibrium expressions for these reactions, water will appear as the activity, rather than concentration. The activity can be approximated by the mole fraction of water. What is the activity of water if this equilibrium is maintained Could this equilibrium exist in seawater, where the mole fraction of water is about 0.98 AG values (kj/mol) gibbsite — 2320.4 kaolinite — 3700.7 quartz —805.0 water —228.4. 

It is possible to carry out this type of kinetic analysis whether a mechanism is simple or elaborate. That is, we can always derive the equilibrium expression for a reaction by applying reversibility and setting forward and reverse rates equal to one another at equilibrium. It is unnecessary to go through this procedure for every chemical equilibrium. As our two examples suggest, inspection of the overall stoichiometry always gives the correct expression for the equilibrium constant. That is, a reaction of the form tjA + iBf ofD + eE has an... 

C16-0005. Write the equilibrium expression for the combustion of NH3 during the s Tithesis of nitric acid ... 

Determine [OH-]gq by setting up a concentration table, solving the equilibrium expression for the unknown, and finding [OH ]g. We know the initial concentrations but must identify x as the change in concentration needed to reach equilibrium. 

Because many species exhibit acid-base properties, it is often possible to write several proton-transfer equilibrium expressions for an aqueous solution. Each such expression is valid if the reactants are species that are actually present in the solution. We have already seen how to focus on the dominant equilibrium consider only those expressions that have major species as reactants, and look for the one with the largest equilibrium constant. 

In principle, the calculation of concentrations of species of a complexation equilibrium is no different from any other calculation involving equilibrium constant expressions. In practice, we have to consider multiple equilibria whenever a complex is present. This is because each ligand associates with the complex in a separate process with its own equilibrium expression. For instance, the silver-ammonia equilibrium is composed of two steps ... 

The overall equilibrium expression for the system can be represented as follows ... 

With the use of the equilibrium expressions for the first three reactions, equation 4.1.22 may be converted to the following form,... 

If you want to prove to yourself that free energies sum, you can write the equilibrium expressions for the first and second reactions and multiply them together, and you ll get the equilibrium expression for the hydrolysis of ATP. Multiplication is equivalent to the addition of logarithms, so that when you multiply equilibrium constants, you re actually adding free energies (or vice versa). 

Siderophore binding sites for iron(III) are for the most part negatively charged and therefore, in aqueous solution there is a competition between H+ and Fe3+ binding. Consequently, the equilibrium expression for the formation of the iron-siderophore complex must take into account proton participation in the reaction. 

An examination of equilibrium expressions for different side-rophore denticities will illustrate nature s preference toward hexadentate siderophores. There is a concentration effect when comparing lower denticity siderophores to their higher denticity analogs. pH-independent equilibrium expressions for generic bidentate and hexadentate siderophores are shown below, where Hx represents a hexadentate siderophore and Bd a bidentate siderophore (charges are omitted for clarity). 

Note Even though the reverse reaction is favored, we still write the equilibrium expression for the reaction as originally written. This is a major point ... 

Plan (1) Calculate the concentration of NH3 from the equilibrium expression for the dissociation of the... 

Step 3 Write an equilibrium expression for the ionization of acetic acid. 

True/False. Water is important in equilibrium expressions for aqueous solutions. 

From our table, we know that the hydroxide ion concentration is x. Therefore, we can substitute 3.0 x 10"3 into the equilibrium expression for x and enter the values into a calculator ... 

With the search variables listed above, the calculation of the remaining molalities (iterative state variables) can be easily performed sequentially by using the equilibrium expressions for the reaction shown in Table 1 and the calculated activity coefficients. The equations are used in the order in which they appear in Table 1. The sequence of calculation of molalities is OH", SO", H2S03, HSO", CO", H CO, CaOH+, CaS0°,... 

Equation 27 is similar to the solid-liquid equilibrium relation used for non-electrolytes. As in the case of the vapor-liquid equilibrium relation for HC1, the solid-liquid equilibrium expression for NaCl is simple since the electrolyte is treated thermodynamically the same in both phases. 

The following Sample Problem shows how to find the equilibrium expression for a reaction. In this chapter, you will use equilibrium expressions for homogeneous reactions (mostly reactions between gases). In Chapters 8 and 9, you will learn how to use equilibrium expressions for heterogeneous systems. 

Write the equilibrium expression for each homogeneous reaction. 

Step 3 Write the equilibrium expression. Substitute the expressions for the equilibrium concentrations into the equilibrium expression. Solve the equilibrium expression for x. 

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