Equilibrium constants and rate coefficients

With a view to determining the equilibrium constant for the isomerisation, the rates of reduction of an equilibrium mixture of cis- and rra/i5-Co(NH3)4(OH2)N3 with Fe have been measured by Haim S . At Fe concentrations above 1.5 X 10 M the reaction with Fe is too rapid for equilibrium to be established between cis and trans isomers, and two rates are observed. For Fe concentrations below 1 X lO M, however, equilibrium between cis and trans forms is maintained and only one rate is observed. Detailed analysis of the rate data yields the individual rate coefficients for the reduction of the trans and cis isomers by Fe (24 l.mole sec and 0.355 l.mole .sec ) as well as the rate coefficient and equilibrium constant for the cw to trans isomerisation (1.42 x 10 sec and 0.22, respectively). All these results apply at perchlorate concentrations of 0.50 M and at 25 °C. Rate coefficients for the reduction of various azidoammine-cobalt(lll) complexes are collected in Table 12. Haim discusses the implications of these results on the basis that all these systems make use of azide bridges. The effect of substitution in Co(III) by a non-bridging ligand is remarkable in terms of reactivity towards Fe . The order of reactivity, trans-Co(NH3)4(OH2)N3 + > rra/is-Co(NH3)4(N3)2" > Co(NH3)sN3 +, is at va-... 

The first evidence that two step proton transfer from a hydrogen-bonded acid could occur consisted of Eigen plots for proton removal by buffer bases. The demonstration of a change in the rate-limiting step as in (30) and (31) provides even more clear evidence and permits the calculation of the rate coefficients and equilibrium constant for opening of the hydrogen bond. 

Transition state (XI) involves electrophilic attack at the group R. However, the sequence of relative rates given in (38) may not necessarily correspond to the relative rates of the appropriate elementary reaction (37), since the rate coefficient in equation (35) is a composite coefficient and includes various rate coefficients and equilibrium constants ol steps prior to reaction (37). 

Note that the nomenclature of the various rate coefficients and equilibrium constants used in this Section is not the same as that used by Roberts. 

A good deal of laboratory data have been obtained recently for the rate coefficients and equilibrium constants for the ternary association reactions of several atmosphere negative ions with H2094,187 191). 

The interest in proton transfer to and from carbon arises partly because this process occurs as an elementary step in the mechanisms of a number of important reactions. Acid and base catalysed reactions often occur through intermediate carbonium ions or carbanions which are produced by reactions (1) and (2). A knowledge of the acid—base properties of carbonium ions or carbanions may also help in understanding reactions in which these species are present as reactive intermediates, even when they are generated by processes other than proton transfer. Kinetic studies of simple reactions such as proton transfer are also important in the development of theories of kinetics. Since both rates and equilibrium constants can often be measured for (1) and (2) these reactions have been useful in the investigation of correlations between rate coefficients and equilibrium constants (linear free energy relations). 

Representative rate coefficients and equilibrium constants at 25°C for the reaction... 

The pH dependence of the rate coefficients and equilibrium constants for all the 1,2-diols listed in Table 1 is of exactly the same form as that found for ethane-... 

RATE COEFFICIENTS AND EQUILIBRIUM CONSTANTS FOR THE OXIDATION OF 1,2-DlOLS... 

The kinetic treatment of the adiabatic polymerization is very complicated with respect to the variation with increasing temperature of rate coefficients and equilibrium constants. Equations derived with a series of simplifying assumptions (e.g. heat capacity of the monomer (Cp m ) = heat capacity of the amorphous polymer (Cp p) = constant = Cp) lead to [2]... 

The individual rate coefficients and equilibrium constants found are collected in Table 24. 

Low pressure rate coefficients and equilibrium constant ratios for HNO, T = 300 K. 

In addition to the continuity equations and the expressions for rate coefficients and equilibrium constants, several further relationships are required in order to close the system of equations. Apart from the expressions for the transport fluxes, these are... 

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