Guldberg and Waage, law

Guldberg and Waage law See mass action law. gult berk and vag-3, 16 ) gum accroldes See acaroid resin. gam a kroi dez)... 

This is the extension to real gases of the Guldberg and Waage law of mass action. By introducing fugacities we have been able to preserve, for all real gases, the same form for the equations for the affinity and the law of mass action as in the case of perfect gases. 

Laws which can be applied at a given temperature will be studied first. a) The Guldberg and Waage law This law can be written as follows ... 

Guldberg and Waage (1867) clearly stated the Law of Mass Action (sometimes termed the Law of Chemical Equilibrium) in the form The velocity of a chemical reaction is proportional to the product of the active masses of the reacting substances . Active mass was interpreted as concentration and expressed in moles per litre. By applying the law to homogeneous systems, that is to systems in which all the reactants are present in one phase, for example in solution, we can arrive at a mathematical expression for the condition of equilibrium in a reversible reaction. 

Within experimental error, Guldberg and Waage obtained the same value of K whatever the initial composition of the reaction mixture. This remarkable result shows that K is characteristic of the composition of the reaction mixture at equilibrium at a given temperature. It is known as the equilibrium constant for the reaction. The law of mass action summarizes this result it states that, at equilibrium, the composition of the reaction mixture can be expressed in terms of an equilibrium constant where, for any reaction between gases that can be treated as ideal,... 

For reversible reactions one normally assumes that the observed rate can be expressed as a difference of two terms, one pertaining to the forward reaction and the other to the reverse reaction. Thermodynamics does not require that the rate expression be restricted to two terms or that one associate individual terms with intrinsic rates for forward and reverse reactions. This section is devoted to a discussion of the limitations that thermodynamics places on reaction rate expressions. The analysis is based on the idea that at equilibrium the net rate of reaction becomes zero, a concept that dates back to the historic studies of Guldberg and Waage (2) on the law of mass action. We will consider only cases where the net rate expression consists of two terms, one for the forward direction and one for the reverse direction. Cases where the net rate expression consists of a summation of several terms are usually viewed as corresponding to reactions with two or more parallel paths linking reactants and products. One may associate a pair of terms with each parallel path and use the technique outlined below to determine the thermodynamic restrictions on the form of the concentration dependence within each pair. This type of analysis is based on the principle of detailed balancing discussed in Section 4.1.5.4. 

In 1862-1863 Berthelot and Pean de Sainte-Jille studied the equilibrium states in etherification reactions. In 1862-1867 Guldberg and Waage, on the basis of Berthelot and Pean de Sainte-Jille s experiments and their own data, suggested a primary formulation of the law of mass action. 

In 1879 Guldberg and Waage substituted the above formulation for the basic law of chemical reactions by its modem version in terms of the concept of mobile equilibrium. For the interaction between the initial substances A, B, C, taken in the stoichiometric ratio of a to to y, i.e. aA + / B + yC, the reaction rate, W, was expressed as... 

Guldberg and Waage (1867) found the effect of reacting substances on a reversible reaction and gave a law known as the law of mass action. According to this law,... 

Looking at chemical kinetics from an historical viewpoint we find that the mass law proposed in 1867 by Guldberg and Waage was the first fundamental contribution to theory. According to this law, now thoroughly established by experiment, the speed of a chemical reaction is proportional to the active masses of the reacting substances, and, as a first approximation, concentrations may be substituted for the active masses. One of the earliest experimental researches in this field was that of Harcourt and Essen in 1880 on the reaction between oxalic acid and potassium permanganate. The several factors involved in this complex reaction were varied, one at a time, and the speed of the reaction was measured experimentally. 

The last equation, one of the most important physicochemical equations, expresses exactly the law of mass action, formulated for the first time by Guldberg and Waage in a less exact form. The equation enables the calculation of the equilibrium composition of a reaction mixture or determination of theoretically possible yields of chemical processes starting from the known value of the equilibrium constant K which can be determined by thermodynamic methods. 

Guldberg and Waage found that the equilibrium concentrations for every reaction system that they studied obeyed this relationship. That is, when the observed equilibrium concentrations are inserted into the equilibrium expression constructed from the law of mass action for a given reaction, the result is a constant (at a given temperature and assuming ideal behavior). Thus the value of the equilibrium constant for a given reaction system can be calculated from the measured concentrations of reactants and products present at equilibrium, a procedure illustrated in Example 6.1. 

Theory of esterification. As was mentioned on p. 298, the experiments of Berthelot and Pean de St. Giles led Guldberg and Waage to the discovery of the law of mass action. The recognition of this law is thus connected historically with the investigation of reactions in solutions. Using the experimental data of Berthelot and Pean de St. Giles to test the constancy of the expression... 

This simple equation, which interrelates the mole fractions of the components in the true equilibrium state, is essentially an expression of Guldberg and Waage s law of mass action. The quantity K T,p) is called the equilibrium constant of the reaction considered. 

Cato Guldberg (1836-1902) and Peter Waage (1833-1900) were Norwegian chemists whose primary interests were in the field of thermodynamics. In 1864, these workers were the first to propose the law of mass action, which is expressed in Equation 9-7. If you would like to learn more about Guldberg and Waage and read a translation of their original paper on the law of mass action, use your Web browser to connect to http //cheniistry.brookscoIe com/skoogfac/. From the Chapter Resources menu, choose Web Works, find Chapter 9, and dick on the link to the paper. 

If the position of an equilibrium (that is, the composition of a chemical reaction system at equilibrium) can depend on the amounts of substances brought together (the active masses as defined by Guldberg and Waage s Law of Mass Action), an important question arises is there a single, measurable property that is unique to any chemical reaction system that can be used to predict its equilibrium composition for all possible initial amounts of the substances involved in the reaction The answer, which of course is yes , first became evident through a careful examination of a reaction studied by Berthollet ... 

Ten years after the law of mass action was propounded by Guldberg and Waage, Willard Gibbs, Professor of Physics in Yale University,... 

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... 

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