Standard free enthalpy reaction

In the gas phase, the variations in standard free enthalpy AG° for the above reactions can be expressed using the redox potentials E° and the excitation energy AEoo, i.e. the difference in energy between the lowest vibrational levels of the excited state and the ground state ... [Pg.92]

Just as the standard enthalpy change for a reaction can be calculated from the standard free enthalpies of formation of the reactants and products, the standard free energy... [Pg.41]

Figure 14.1 Standard free enthalpy (AG°) of formation (normal lines) of chromium oxides and carbides and standard free enthalpy (AG°) of reaction (lines with squares) of chromium with methane as a function of temperature.

One can also derive a relationship between temperature and the equilibrium constant Keq and the standard free enthalpy AH°. If the following reversible reaction is operational... [Pg.32]

The change of the cell voltage as a function of the cell temperature (temperature coefficient) dEf fdT = -0.83xl0-4 VK 1 and the relationship between the standard reaction entropy and the standard free enthalpy of reaction (3AG /3T)p = -AS the value for the cell reaction can be calculated as -AS = -16.02 J K-1 mol-1. Refs. [i] Bockris JO M, Reddy AKN, Gamboa-Aldeco M (2000) Modern electrochemistry, vol 2A. Kluwer, Dordrecht, p 1356 [ii] Holze R (1989) Leitfaden der Elektrochemie. Teubner, Stuttgart [iii] Handel S (1971) A dictionary of electronics. Penguin Books, London [iv] Rieger PH (1994) Electrochemistry. Chapman-Hall, New York, p 2... [Pg.136]

Because AG, AH, and AS are temperature dependent, they must be calculated at a certain temperature. Values of thermodynamic functions at 298.15° K (or 25° C) for many chemical compounds are tabulated. For a large number of organic compounds, the decomposition reactions at standard temperature of 25° C have negative values for the standard free enthalpy AG °. These reactions should, therefore, occur spontaneously. However, their reaction rates are in most cases slow enough (see Section 3.2) such that this assures the chemical stability of numerous organic... [Pg.33]

The free enthalpy accompanying the reaction is the difference in the standard free enthalpies of the products and the reactants. Similar expressions are true for the enthalpy and the entropy of the system with expressions given below ... [Pg.60]

AG° is the standard free enthalpy change for the reaction at the prescribed temperature, II is the multiplication operator, a and v are the activity (fuga-city, for gaseous species) and stoichiometric coeffic-... [Pg.35]

The standard free enthalpy change for a chemical reaction can be calculated from tabulated values of various thermodynamic functions (1- ) For aqueous chemical reactions at 25 C, the standard free enthalpy change is computed from... [Pg.36]

Standard free enthalpy of Fe e is equal to 0, and for Fe it is about -20.3 kcal-mole f So that standard free enthalpy of this reaction is equal to 20.3 kcal mole f Then... [Pg.90]

Dissociation constant of this reaction under standard conditions (25 °C) may be calculated from values of standard free enthalpy of the formation of H, OH" and H O ... [Pg.101]

The calculation is to be based upon change in standard free enthalpy (AG ) of those cell reactions where I, II and III, respectively are eombined with the standard hydrogen reaction, as shown in the following table ... [Pg.33]

This property, A G , is also the standard free enthalpy of reaction (f) ... [Pg.94]

Afil AfHf standard free enthalpy of formation of Cj standard enthalpy of formation of Cj standard free enthalpy of reaction i J mol l J mol l... [Pg.325]

AG — standard free enthalpy of reaction AH% — standard enthalpy of reaction AS = standard entropy of reaction... [Pg.725]

Knowledge of the standard free enthalpy of this reaction allows calculation of oxygen partial pressure to be put in equation (B) ... [Pg.446]

Assuming, for the sake of simplicity, that in all cases reactions at 500 K will be accompanied by a change in standard free enthalpy equal to —1000 cal mol plot for every reaction the course of free enthalpy of the system in dependence on the loss of initial constituents, and show that this relationship is of convex character, having a minimum identical with that which can be calculated from the relation... [Pg.51]

In cases where the reaction to be studied can be carried out in a reversible galvanic element, the change of standard free enthalpy related to bringing the constituents into a state of equilibrium, is given by the relationship... [Pg.200]

It is possible to expand this scheme to helix-helix displacement reactions, i.e. the mutual exchange of strands between two metastable helical complexes to form the two thermodynamically most stable double helical species out of the four single strands involved. This particular type of a displacement reaction can be illustrated by the following thermodynamic cycle [poly(rA)-poly(dU)] + [poly(dA)-poly(rU)] [poly (dA) poly(dU)] -I- [poly(rA) poly(rU)]. If all components are in their standard states the standard free energy can be listed for each of the helix-formation reactions. The difference between the standard free enthalpies of the final states and the initial states is the displacement free enthalpy AG of polyfdA) from the one and poly(rU) from the other helix. Energetics of strand-exchange between two helical complexes Cpoly(A) poly (B)]fc -I- [poly (C) poly [poly(A) poly (Q -I- [poly(B) polyfD)] ... [Pg.253]

NMR chemical shift (most often given vs. TMS) redox reorganization energy parameter when AG° = 0 carbonyl infrared freqnency reaction activation enthalpy standard free enthalpy of the reaction... [Pg.591]

The standard potentials of the new couples are calculated from those of the initial couples according to the general principles already given (see Chap. 2). The halfredox reactions in which a precipitation reaction or a complexation reaction occurs can always be decomposed into a pure redox equilibrium and into another one that can be a reaction of precipitation or of complexation. For the calculations, we must add the corresponding standard free enthalpies. Thus,... [Pg.236]

In mass spectrometry, the proton affinity parameter is used more than basicity. The proton affinity of a molecule M is the standard enthalpy of reaction [designated delta H (AH)] associated with the reaction MH+ M + H+ in the gas phase. The higher the AH value, the more energy that must be supplied to remove a proton from M. The basicity of M corresponds to AG (standard free enthalpy of reaction) of the same reaction. Thus, AG = AH - TAS, where T is the temperature of the system and AS is the entropy variation. AS is generally difficult to determine. For that reason, mass spectrometrists generally utilize proton affinities. Table 3.1 in Chapter 3 lists the proton affinity values of the main families of organic compounds. [Pg.161]

The standard free energies, enthalpies, and entropies calculated from the experimental data for the reaction 4Me + Hj = 2Me2H (where Me = Pd or Ni), at 1 atm of hydrogen pressure and 298°K. [Pg.250]

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