Kinetics of Soil Chemical Reactions-A Theoretical Treatment

2015 ◽  
pp. 1-18 ◽  
Author(s):  
Chaim Aharoni ◽  
Donald L. Sparks
Keyword(s):  
Chemical Reactions ◽  
Theoretical Treatment ◽  
Kinetics Of

New highly efficient coulometric cell with homogenous potential distribution on the working electrode

1986 ◽  
Vol 51 (3) ◽  
pp. 636-642
Author(s):  
Michal Németh ◽  
Ján Mocák
Keyword(s):  
Chemical Reactions ◽  
Potential Distribution ◽  
Anaerobic Conditions ◽  
Highly Efficient ◽  
Working Electrode ◽  
Constant Potential ◽  
Quantitative Analyses ◽  
Mechanism And Kinetics ◽  
Kinetics Of

A highly efficient coulometric cell was designed and constructed, ensuring a constant potential over the whole surface of the working electrode and suitable for very rapid electrolysis. It consists of concentric cylindrical Teflon parts; also the working and auxiliary electrodes are cylindrical and concentric. Electrolysis can be carried out under anaerobic conditions. Functioning of the cell was tested on the oxidation of hexacyanoferrate(II) and chlorpromazine and reduction of hexacyanoferrate(III). The new cell is suitable for routine quantitative analyses and in studying the mechanism and kinetics of moderately rapid chemical reactions.

Kinetics of homogeneous chemical reactions

2005 ◽  
Author(s):  
Boris S. Bokstein ◽  
Mikhail I. Mendelev ◽  
David J. Srolovitz
Keyword(s):  
Chemical Reactions ◽  
Irreversible Thermodynamics ◽  
Kinetic Process ◽  
Chemical Reaction Kinetics ◽  
Long Time ◽  
Homogeneous Chemical ◽  
Parallel Reactions ◽  
Diffusive Processes ◽  
Kinetics Of

Kinetics considers the rates of different processes. Chemical kinetics refers to the rates and mechanisms of chemical reactions and mass transfer (diffusion). Recall that since thermodynamic equilibrium implies that the rates of all processes are zero, time is not a thermodynamic variable. Rather, time is the new parameter introduced by the consideration of kinetic processes. The rate of a kinetic process and how it depends on time is determined, in part, by the degree of the deviation from equilibrium. If the deviation from equilibrium is small, the rate decreases (without changing sign) as the system approaches equilibrium. If the deviation from equilibrium is large, the situation is more complicated. For example, non-monotonic (including oscillatory) processes are possible. The sign of the rate can change during such processes; that is, the reaction can proceed in one direction and then the other. Additionally, if the deviation from equilibrium is large, small changes to the system can produce very large changes in the rate of the kinetic process (i.e. chaos). Non-equilibrium, yet nearly stationary states of the system can arise (i.e. states that exist for a very long time). Finally, if the deviation from equilibrium is very large, the system can explode (i.e. the process continues to accelerate with time). In this chapter, we develop a formal description of the kinetics of rather simple chemical reactions. Consecutive and parallel reactions will also be considered here. A more general approach (irreversible thermodynamics) will be considered in Chapter 9. In Chapter 10, we examine diffusive processes. Then, in Chapter 11, we consider the kinetics of heterogeneous processes. In order to start the study of chemical reaction kinetics, we must first define what we mean by the rate of reaction. Consider the following homogeneous reaction: . . . Cl2 + 2NO → 2NOCl. (8.1) . . .

scholarly journals Chemical reactions during sintering of Fe-Cr-Mn-Si-Ni-Mo-C-steels with special reference to processing in semi-closed containers

2015 ◽  
Vol 47 (1) ◽  
pp. 61-69 ◽  
Author(s):  
A. Cias
Keyword(s):  
Mechanical Properties ◽  
Carbon Monoxide ◽  
Special Reference ◽  
Water Vapour ◽  
Chemical Reactions ◽  
Thermodynamic Data ◽  
Alloying Elements ◽  
Bearing Steels ◽  
Kinetics Of

Sintering of Cr, Mn and Si bearing steels has recently attracted both experimental and theoretical attention and processing in semiclosed containers has been reproposed. This paper brings together relevant thermodynamic data and considers the kinetics of some relevant chemical reactions. These involve iron and carbon, water vapour, carbon monoxide and dioxide, hydrogen and nitrogen of the sintering atmospheres and the alloying elements Cr, Mn, Mo and Si. The paper concludes by presenting mechanical properties data for three steels sintered in local microatmosphere with nitrogen, hydrogen, nitrogen-5% hydrogen and air as the furnace gas.

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