Stoicheiometry defined

In the broadest sense, I found the analogy with fluid mechanics to be very helpful. Just as kinematics provides the geometrical framework of fluid mechanics by exploring the motions that are possible, so also stoicheiometry defines the possible reactions and the restrictions on them without saying whether or at what rate they may take place. When dynamic laws are imposed on kinematic principles, we arrive at equations of motion so, also, when chemical kinetics is added to stoicheiometry, we can speak about reaction rates. In fluid mechanics different materials are distinguished by their constitutive relations and allow equations for the density and velocity to be formulated thence, various flow situations are examined by adding appropriate boundary conditions. Similarly, the chemical kinetics of the reaction system allow the rates of reaction to be expressed in terms of concentrations, and the reactor is brought into the picture as these rates are incorporated into appropriate equations and their boundary conditions. 

A-i) so far known were obtained. The crystal structure of the defect silicide MnSi ( = 0.25—0.30) has been determined and its stoicheiometry defined as Mn2,Si47. New LnSng compounds of face-centred cubic structure (AuCug type) have been prepared for Tb, Dy, Ho, Er, and Y (Table 43) under high pressures (85 kbar) and temperatures (1400 °C) analogous compounds have not been observed in the Lu-Sn and Sc-Sn systems. The magnetic susceptibility and electrical resistivity of the compound EuSng have been determined as a function of temperature (10—300 K). The... 

Any considered mechanism must, first of all, be consistent with the thermodynamic constraints of the system. Such limits are set by the span of oxidoreduction potentials in the respiratory chain and by the protonmotive force that opposes the proton movement. The relative magnitudes of these two forces set an absolute upper limit for H" /e stoicheiometry of proton translocation. The stoicheiometry in turn, puts limits on the underlying mechanisms. Analogous limits for the H /ATP stoicheiometry of ATP synthesis are obtained from the relative magnitudes of phosphorylation potential and pmf. An elementary thermodynamic analysis of the system can therefore be helpful in defining the degree of freedom in discussions of chemical mechanisms (see Ref. 8). 

The stoicheiometry of the complexes formed by oxovanadium(iv) with gluconate varies from M L = 1 1 at pH 6.0 to 1 2 above pH 12. Both species exhibit well-defined polarographic oxidation waves. The oxidation half-wave potential is independent of gluconate concentration for the 1 1 species but not for the 1 2 species. Independent n.m.r. evidence indicates that gluconate does not complex with at high pH so that the oxidation reaction is formulated as ... 

Table 5 Rate constants and activation parameters for non-complementary redox reactions involving two metal ion complexes. The expression in the column headed Rate is defined so that for a reaction of stoicheiometry aA + bB+. .. products, the rate is given by Rate = — (l/a)d[A]/df= — (l/6)d[B]/df etc. For other conventions, see Table 3...

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