RATE OF HOMOGENEOUS

The progress of this category of reactions is expected to depend on the composition of the materials within the phase as well as the temperature and pressure of the system. The rate of homogeneous reaction should not be affected by the shape of the container, the surface properties of the solid materials in contact with the phase, and the diffusion characteristics of the fluid. Thus the rate of reaction of component i may be expressed as... 

Nucleation can occur either homogeneously or heterogeneously. Homogeneous nucleation occurs when random molecular motion in the molten state results in the alignment of a sufficient number of chain segments to form a stable ordered phase, known as a nucleus. The minimum number of unit cells required to form a stable nucleus decreases as the temperature falls. Thus, the rate of nucleation increases as the temperature of the polymer decreases. The rate of homogeneous nucleation also increases as molecular orientation in the molten polymer increases. This is because the entropy difference between the molten and crystalline states diminishes as molecular alignment in the molten state increases. 

Effect of Microwaves on the Rates of Homogeneous Reactions in Open Vessels 1123... 

Figure 15.9. Effect of supersaturation on the rates of homogeneous and heterogeneous nucleation.

The theory of premixed flames essentially consists of an analysis of factors such as mass diffusion, heat diffusion, and the reaction mechanisms as they affect the rate of homogeneous reactions taking place. Inasmuch as the primary mixing processes of fuel and oxidizer appear to dominate the burning processes in diffusion flames, the theories emphasize the rates of mixing (diffusion) in deriving the characteristics of such flames. 

What factors afiect the rate of homogeneous and heterogeneous chemical reactions What is called the order of a reaction Give-examples of first- and second-order reactions. Write a mathematical expression of the law of mass action for a first- and second-order irreversible reactions. 

Comparison of the Rates of Homogeneous and Heterogeneous Redox Reactions... 

There is homogeneous reaction in the process tube as well as heterogeneous reaction on the inside of the tube wall. Assume that the net rates of homogeneous and surface reaction of the steam may be represented as... 

Christian Reichardt, Solvent effects on the rate of homogeneous reactions in solvents and solvent effects in organic chemistry, 2nd ed., Wiley-VCH Verlag GMBH Co. Wiley-VCH Publishers, New York,... 

Homogeneous Nucleation (a) Using Eq. 8.6-2, calculate the rate of homogeneous nucleation of styrene as a function of temperature at atmospheric pressure and a temperature range from 145°C to 325°C. In calculating the pressure in the bubble, assume that it equals the vapor pressure (extrapolate it from lower temperature values). Use the Eotvos equation a = 2.1 (p/M)1 (Tc — T — 6), where the surface tension is in erg/cm3, temperature is in °C, and density in g/cm3, to evaluate the surface tension as a function of temperature. The critical temperature... 

Effects of Supercritical Solvents on the Rates of Homogeneous Chemical Reactions... 

Three processes can control the rate of homogeneous charge transport through a redox-active polymer film, i.e. electron self-exchange between redox-active centers,... 

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