What is the Law of Mass Action

What is the law of mass action Is it true that the value of K depends on the amounts of reactants and products mixed together initially Explain. Is it true that reactions with large equilibrium constant values are very fast Explain. There is only one value of the equilibrium constant for a particular system at a particular temperature, but there is an infinite number of equilibrium positions. Explain. 

Any one of these expressions for fCa represents what is known as Ostwald s dilution law, which has essentially been obtained by applying the law of mass action to solutions of weak electrolytes. It deals with the variation in the degree of dissociation with concentration or dilution of solutions of weak electrolytes. It is not applicable to solutions of strong electrolytes. The failure of strong electrolytes to obey Ostwald s dilution law is known as the anomaly of strong electrolytes. 

Apply the law of mass action to work out the proportion of receptors in the active form (pactive) for the mechanism for receptor activation shown in Figure 1.14. What will be the value of EC50 under these circumstances (Assume that the response measured is directly proportional to p,iCtlve and that the concentration of the G protein can be regarded as constant.)... 

Probably an example and problems derived from the carbon dioxide-blood buffer system in humans should be in every physical chemistry course. What a rich, complex example this is from Henry s law for the solubility of carbon dioxide in water (blood) to buffer capacity, that is, the rate of change of the law of mass action with proton concentration. The example can be expanded to include nonideal solutions and activities. How many physical chemistry courses use this wonderful and terribly relevant to life example First-year medical students learn this material. 

What factors afiect the rate of homogeneous and heterogeneous chemical reactions What is called the order of a reaction Give-examples of first- and second-order reactions. Write a mathematical expression of the law of mass action for a first- and second-order irreversible reactions. 

Explain why the equality of the hydrogen ion and hydroxyl ion concentrations is violated when certain salts are dissolved in water. Compare the values of the dissociation constants of water, acetic acid, carbonic acid, the bicarbonate ion, and aluminium hydroxide. How can the hydrolysis process be explained from the viewpoint of the law of mass action In what cases is hydrolysis reversible and in what cases does it proceed virtually to the end ... 

Pour 2 ml of a 25% ammonia solution into a test tube and throw a small piece of sodium hydroxide into it. What happens Explain the observed phenomenon on the basis of the law of mass action. What processes are used to produce ammonia in the industry Where is ammonia used ... 

Explain from the standpoint of the law of mass action why dry sodium nitrate (saltpetre) and a concentrated sulphuric acid solution are taken to prepare a concentrated nitric acid solution. Why does the reaction mixture have to be heated, but carefully What are the boiling points of sulphuric and nitric acids How do nitric acid solutions of various concentrations behave when heated What is the composition of an azeotropic mixture of nitric acid with water ... 

For linear mechanisms we have obtained structurized forms of steady-state kinetic equations (Chap. 4). These forms make possible a rapid derivation of steady-state kinetic equations on the basis of a reaction scheme without laborious intermediate calculations. The advantage of these forms is, however, not so much in the simplicity of derivation as in the fact that, on their basis, various physico-chemical conclusions can be drawn, in particular those concerning the relation between the characteristics of detailed mechanisms and the observable kinetic parameters. An interesting and important property of the structurized forms is that they vividly show in what way a complex chemical reaction is assembled from simple ones. Thus, for a single-route linear mechanism, the numerator of a steady-state kinetic equation always corresponds to the kinetic law of the overall reaction as if it were simple and obeyed the law of mass action. This type of numerator is absolutely independent of the number of steps (a thousand, a million) involved in a single-route mechanism. The denominator, however, characterizes the "non-elementary character accounting for the retardation of the complex catalytic reaction by the initial substances and products. 

The single-molecule nature of the gene allows the gene in steady state to behave much differently from what the macroscopic laws postulate. Even the law of mass action is modified as seen in Fig. 28.4. Again, most models of gene regulation have assumed macroscopic equilibrium behavior and would obey the law of mass action but this simple picture breaks down due to singlemolecule effects. 

Mutual incomprehensibility, and a babel of tongues characterise our times. The reasons lie beyond the present questioning of the foundations that concern physicists on the one hand, and evolutionists on the other. They lie beyond the fact that what is axiomatic to one discipline can hardly be acc ted for anodier. For example the "law of mass action" is a beginning for a chemist and the end for a physicist who can go no further without questioning the foimdations. 

Despite their success in giving the correct expressions for the mass action law, the empirical procedures leave unanswered numerous fundamental questions about chemical equilibrium. Why should the law of mass action exist in the first place, and why should it take the particular mathematical form shown here Why should the equilibrium constant take a unique value for each individual chemical reaction What factors determine that value Why does the value of the equilibrium constant change slightly when studied over broad ranges of concentration Why should the equilibrium constant depend on temperature Is there a quantitative explanation for the temperature dependence ... 

What all this means in practice is that drugs are absorbed quite effectively from the small intestine even if they exist in a predominantly ionised form. The absorption process obeys the law of mass action, which was introduced in Chapter 1. This law is fundamentally an equilibrium process, and, as with any equilibrium, rapid removal of the products or compounds on the right-hand side of the equilibrium arrow will shift the equilibrium in that direction. This is exactly what happens in drug absorption across the gut membrane a small amount of unionised drug is absorbed by passive diffusion and whisked away by the rich blood supply of... 

The Law of Mass Action is thus essentially the statement that the equilibrium composition of a reaction mixture can vary according to the quantities of components that are present. This of course is just what Berthollet observed in his Egyptian salt ponds, but it was now seen to be a consequence of the dynamic nature of chemical equilibrium. 

By virtue of what is called the law of mass action, the buildup of product itself works against the conversion reaction. Thus, the very buildup of lactic acid or lactate product serves as an inhibitor. (Albeit pyruvic acid is also listed as an inhibitor in the compilations, but which is a reactant for the conversion to lactic acid.) Another inhibitor listed is oxalic acid, a naturally occurring component of such vegetables as spinach and rhubarb, and which becomes toxic in large amounts. The common... 

In 1863 Guldberg and Waage described what we now call the law of mass action, which states that the rate of a chemical reaction is proportional to the active masses of the reacting substances present at any time. The active masses may be concentrations or pressures. Guldberg and Waage derived an equihbrium constant by defining equihbrium as the condition when the rates of the forward and reverse reactions are equal. Consider the chemical reaction... 

We have made a distinction between an overall reaction and its elementary steps in discussing the law of mass action and the Arrhenius equation. Similarly, the basic kinetic laws treated in this section can be thought of as applying primarily to elementary steps. What relationships exist between these elementary steps and the overall reaction In Table 1.1 we gave as illustrations the rate laws that have been established on the basis of experimental observations for several typical reactions. A close look, for example, at the ammonia synthesis result is enough to convince one that there may be real difficulties with mass action law correlations. This situation can extend even to those cases in which there is apparent agreement with the mass action correlation but other factors, such as unreasonable values of the activation energy, appear. Let us consider another example from Table 1.1, the decomposition of diethyl ether ... 

An example with simpler numbers will clarify these equilibrium shifts. Table 2-2 is for a hypothetical case of Q about 9. No matter what proportions are taken to start, the changes linked by the reactions proceed until the Q value is attained. This is a statement of the law of mass action, which was formulated by Guldeberg and Waage in 1865. Van t Hoff in 1877 gave the kinetic explanation that such a relation must follow if rates of opposing reactions become equal when the equilibrium concentrations are reached. 

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