Chemical kinetics is study of the rates of chemical process, Chemistry

 

Chemical kinetics is study of the rates of chemical processes.                                                                        

The detailed explanation at molecular level how a reaction proceeds is known as reaction mechanism. The steady-state approximations is a method for deriving a rate law from the proposed mechanism.                                                                                                                   

RATE OF REACTION: Chemical kinetics deals with experimental determination of the reaction rates from which rate laws and rate constants are derived. Relatively simple rate laws exist for zero-order reactions (for which reaction rates are not dependent on the concentration), 1st-order reactions, and 2nd-order reactions, and can be derived for others. In the consecutive reactions the rate-determining step  determines the kinetics.     

                                                                        LAW OF MASS ACTION: The law of mass action states that speed of the chemical reaction is proportional to quantity of the reacting substances.                                                                                                                                              

ARRHENIUS EQUATION: The Arrhenius equation gives " dependence of the rate constant k of the chemical reactions on temperature T  and activation energy Ea", as shown below: 

Here A is pre-exponential factor or the prefactor and R is gas constant.

TRANSITION STATE THEORY: Another Arrhenius-like expression is their in the "transition state theory" of the chemical reactions    

Here ΔG‡ is the Gibbs free energy of activation, kB is the Boltzmann's constant, and h is Planck's constant.

FACTORS INFLUENCE REACTION RATES: A number of factors influence the rates of chemical reactions, and these are summarized as follows;

 

1.      Nature of Reactants

 

2.      Temperature

 

3.      Concentration Effect

 

4.      Heterogeneous reactions

 

5.      Catalysts

Applications: While performing the catalytic cracking of heavy hydrocarbons into gasoline and light gas, for instance, kinetic models can be used to find temperature and pressure at which the highest yield of the heavy hydrocarbons into gasoline will take place. The mathematical models which describe chemical reaction kinetics provide chemists and chemical engineers with the tools to better understand and describe chemical processes such as microorganism growth, stratospheric ozone decomposition, food decomposition, and the complex chemistry of biological systems. These models can also be used in the design or modification of chemical reactors to optimize the product yield; more efficiently separate products, and remove environmentally harmful by-products. 

 

Posted Date: 9/14/2012 9:26:28 AM | Location : United States







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