Zeroth-order rate constant

TABLE 3.1 Zeroth-order rate constants for nitrations in organic solvents... 

Data for zeroth-order nitration in these various solvents are given in table 3.1. Fig. 3.1 shows how zeroth-order rate constants depend on the concentration of nitric acid, and table 3.2 shows how the kinetic forms of nitration in organic solvents depend on the reactivities of the compounds being nitrated. 

The dependence of the zeroth-order rate constants on the concentration of acetyl nitrate is shown in fig. 5.1 in the absence of added acetic acid the rate increases according to the third power of the concentration of acetyl nitrate, but when acetic acid is added the dependence becomes... 

The nitration in acetic acid of mesitylene, p-xylene, ethylbenzene and toluene ([aromatic] > 4 x io-2 mol l-1) was zeroth-order in the concentration of the aromatic compound.9 Values of the zeroth-order rate constants at 20 °C were 4 25 x io-6 mol l-1 s 1 ([HNOs] = 5 0 mol l-1) and 6 o x io-5 mol l-1 s 1 ([HN03] = 7 0 mol l-1). The nitration of benzene could be brought under the control of a zeroth-order rate... 

For a particular experiment in a packed catalytic tubular reactor, the chemical kinetics can be approximated by a zeroth-order rate law where the best value for the zeroth-order rate constant is calculated via the formalism on pages 459 and 460. At what value of the intrapeUet Damkohler number Aa. intrapellet does reactant A occupy 75% by volume of the catalyst if the porous pellets are (a) spherical, (b) long cylinders, and (c) wafer-like ... 

Table 4. Temperature Dependency of Zeroth-Order Rate Constant.

Figure 5 shows triclosan concentrations as a function of electrolysis time in ethanol solutions at current densities of 15 and 25 mA/cm. The linear decline in triclosan concentrations with time indicates diat die destruction kinetics were zerodi order in triclosan concentration. This can be explained by a reaction that was limited by the oxidation current. This conclusion is supported by con arison of the removal rates at 15 and 25 mA/cm. The zeroth order rate constant at 25 mA/cm of 2.2 x 10 mol/min is a factor of 1.47 greater than the rate constant of 1.5 x 10 mol/min at 15 mA/cm This ratio is close to the factor of 1.67 difference between the two current densities. 

That is, the rate of disappearance of A is a constant, the zeroth-order rate constant. These types of reactions are rare, but they do occur for example, conversion of ingested ethyl alcohol (CHjCHjOH) into acetaldehyde (CH3CITO) in the body follows zeroth-order kinetics. 

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