Gibbs free energy change, chemical reaction

Having calculated the standai d values AyW and S" foi the participants in a chemical reaction, the obvious next step is to calculate the standard Gibbs free energy change of reaction A G and the equilibrium constant from... 

To apply the preceding concepts of chemical thermodynamics to chemical reaction systems (and to understand how thermodynamic variables such as free energy vary with concentrations of species), we have to develop a formalism for the dependence of free energies and chemical potential on the number of particles in a system. We develop expressions for the change in Helmholtz and Gibbs free energies in chemical reactions based on the definition of A and G in terms of Q and Z. The quantities Q and Z are called the partition functions for the NVT and NPT systems, respectively. 

Calculate the change in Gibbs free energy for chemical reactions and identify temperature ranges in which a particular reaction is spontaneous (Section 13.7, Problems 35 0). 

A chemical reaction will proceed to products in significant yield only if the standard Gibbs free energy change of reaction AG° is negative or at worst slightly positive, since the equilibrium constant K° for the reaction under standard conditions is... 

Calculation of Standard Change of Gibbs Free Energy for Chemical Reactions from Gibbs Free Energy of Formation... 

Gibbs free energy change on reaction reaction enthalpy enthalpy (specific) enthalpy, Henry s law constant electric current diffusive mass flux conduction heat flux W m reaction velocity thermal conductivity Boltzmann constant chemical equilibrium constant resistance coefficients effective thermal conductivity first-order reaction rate constant characteristic half thickness Lewis number... 

The basic criterion for equilibrium with respect to a given chemical reaction is that the Gibbs free energy change associated with the progress of the reaction be zero. 

The Gibbs free energy change involved in reaction 5.201 is given by the sum of the chemical potentials of components in reaction (p.,), multiphed by their respective stoichiometric factors (v,)—i.e.,... 

Equation (5) shows the fundamental relationship between Gibbs free energy change of the chemical reaction and the cell potential under reversible conditions (potential of the electrochemical cell reaction). 

An important motivation for studying entropy changes at low temperature is to obtain reaction entropies AS (5.76) that could be combined with thermochemically measured reaction enthalpies A7/rxn to give the Gibbs free energy changes for chemical reactions. Starting from the observation that... 

How do we weigh the contributions of changes in both heat (AH) and randomness (AS) to the overall spontaneity of a process To take both factors into account when deciding the spontaneity of a chemical reaction or other process, we define a quantity called the Gibbs free-energy change (AG), AG = AH — TAS. 

We represent A///° and A/G° as the standard enthalpy and Gibbs free energy changes for the reaction in which the chemical substance is formed from the elements in their stable form, as they occur in nature at T = 298.15 K.rr For ions in solution, the values tabulated are relative to the standard enthalpy and Gibbs free energy of formation of the H+ ion being set equal to zero.ss... 

The standard enthalpy and Gibbs free energy changes for a chemical reaction can be calculated from A./H° and A/G° data using the relationships... 

The value of the Gibbs free energy change for a chemical reaction at the temperature specified is given by the difference in Gibbs free energy between the products and the reactants. 

The direction of chemical reactions can always be predicted from thermodynamical data. Thus, if the Gibbs free energy change of a reaction is calculated,... 

It is customary to work with the equilibrium constants Kx, Kc, Km that are related to standard conditions, i.e., to standard rather than reference chemical potentials. Then the superscripts in AG X, AGdc, AG refer to the differential Gibbs free energy changes accompanying the reaction - 0 in... 

The standard Gibbs free energy changes accompanying a chemical reaction are handled in a manner completely analogous to that described in the preceding subsections. By convention,... 

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