Question
Thu April 21, 2011 By: Rohit Kumar

what are consecutive reactions ? how do we solve reactions involving these type of reactions where the rate constants of the reactions is given?

Expert Reply
Sat April 23, 2011

Chemical processes in which the product of one reaction is the precursor or the  initial material for other reactions, are consecutive reactions. Consecutive reactions include chemical processes such as polymerization and thermal cracking and chlorination of hydrocarbons. In cracking, the consecutive conversion of macro-molecular compounds into compounds of lower and lower molecular weight takes place at the same time as consecutive processes of formation of macromolecular hydrogen-poor compounds, such as coke. The compounds CH3Cl, CH2Cl2, CHCl3, and CCl4 are formed consecutively upon chlorination of methane.

An example of a simple consecutive reaction is the consecutive occurrence of two irreversible first-order reactions A ? B ? C, where A, B, and C are certain substances. The change in concentration of the substances may be calculated by integrating a system of two kinetic equations. The calculation shows that the concentration of intermediate compound B at first increases to a maximum and then decreases.

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