Gibbs energy change equilibrium constants

Quantity K is the chemical reaction equilibrium constant for reactionyj and AG° is the corresponding standard Gibbs energy change of reaction (eq. 237). Although called a constant, fC is a function of T, but only of T. 

The Gibbs energy changes of the reaction are given at the temperatures in the table. The units are cal/gmol dimethyl ether. Confirm the tabulated values of the equilibrium constant, K, and of the fractional conversion, x, of the methanol. 

Calculate the equilibrium constant and the standard Gibbs energy change at 25°C for reaction 3 from the equilibrium constants obtained above for reactions 1 and 2. Show that AG° for reaction 3 = AG° of reaction 1 - AG° of reaction 2. 

NAD+ is a coenzyme for both pyruvate dehydrogenase and ethanol dehydrogenase. Using the values of E0 from Table 6-8 calculate the Gibbs energy change and the equilibrium constant for the reaction. 

Calculate the standard Gibbs energy changes and equilibrium constants in terms of species for the following reactions at... 

Calculate the standard Gibbs energy changes and equilibrium constants in terms of species for the following reactions at 298.15 K and ionic strengths of 0, 0.10, and 0.25 M. Summarize the calculations in two tables. 

The standard Gibbs energy change, AG° (still often called standard free energy, but this term should be avoided), is related to the equilibrium constant by equation (6). 

Relationship between Equilibrium Constant, Kp/po and Gibbs Energy Change, A G°... 

The effect of temperature on a chemical reaction at equilibrium can be described quantitatively by considering the change in a thermodynamic equilibrium constant with temperature. As demonstrated in Special Topic 1 at the end of this chapter, the thermodynamic equilibrium constant is related formally to the Gibbs energy change lor a reaction, with all reactants and products in their Standard Slates ... 

The Gibbs energy change is related to some other important physical quantities, such as the equilibrium constant for a chemical reaction and the electromotive force of an electrochemical cell, by the Nemst and van t Hoff equations ... 

Calculation of equilibrium conversions is based on the fundamental equations of chemical-reaction equilibrium, which in application require data for the standard Gibbs energy of reaction. The basic equations are developed in Secs. 15.1 through 15.4. These provide the relationship between the standard Gibbs energy change of reaction and the equilibrium constant. Evaluation of the equilibrium constant from thermodynamic data is considered in Sec. 15.5. Application of this information to the calculation of equilibrium conversions for single reactions is taken up in Sec. 15.7. In Sec. 15.8, the phase role is reconsidered finally, multireaction equilibrium is treated in Sec. I5.9.t... 

THE STANDARD GIBBS ENERGY CHANGE AND THE EQUILIBRIUM CONSTANT... 

Nernst equation — A fundamental equation in -> electrochemistry derived by - Nernst at the end of the nineteenth century assuming an osmotic equilibrium between the metal and solution phases (- Nernst equilibrium). This equation describes the dependence of the equilibrium electrode - potential on the composition of the contacting phases. The Nernst equation can be derived from the - potential of the cell reaction (Ecen = AG/nF) where AG is the - Gibbs energy change of the - cell reaction, n is the charge number of the electrochemical cell reaction, and F is the - Faraday constant. 

By applying the well-known relationship between the Gibbs-energy change and the equilibrium constant (8) to the above scheme, one finds ... 

Since, for equilibria, the logarithm of the equilibrium constant is proportional to the standard molar Gibbs energy change, AG°, according to Eq. (4-3),... 

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