CLASSIFICATION OF CHEMICAL REACTION

Chemical reaction is classified according to number of reaction react to form specific product as follows

1. Single reaction
2. Multiple reaction
3. Combine reaction

Single reaction :- 

• As name suggest only one reaction takes part to form specific product.
• When a single stoichiometric equation and single rate equation are chosen to represent the progress of the reaction, we can called reaction as single reaction

Multiple reaction :-

• When more than one stoichiometric equation is chosen to represent the observed changes then more than one kinetic expression is needed to follow the changing composition of all the reaction components, then we can say its multiple reactions.
• Multiple reactions may be classified as:

• Series reactions

• Parallel reactions:-  which are of two types
• Competitive reaction

• Side by side reaction

Combine reaction

• In combine reaction, reaction proceeds in parallel with respect to B, but in series with respect to A, R, and S.

Chemical reaction classified according to relation between rate of reaction and stoichiometric equation of that reaction

1. Elementary Reactions 
2. Nonelementary Reactions

Elementary Reactions:- 

• The reactions in which the rate equation corresponds to a stoichiometric equation are called elementary reactions
• An elementary reaction is a chemical reaction in which one or more chemical species react directly to form products in a single reaction step and with a single transition state.
• Elementary reactions are single step reactions.
• Elementary reactions are simple in nature.
• For an elementary reaction, the order of reaction must be an integer.
• In a unimolecular elementary reaction, a molecule A dissociates or isomerises to form the products(s)

the rate of disappearance of A is

• In a bimolecular elementary reaction, two atoms, molecules, ions or radicals, A and B, react together to form the product(s)

the rate of disappearance of A is

Nonelementary Reactions:- 

• When there is no direct correspondence between stoichiometry and rate equation, then we can called as nonelementary reactions
• Non elementary reactions are multi-step reactions , i.e , such reactions occur through a series of reaction steps. 
• The non elementary reactions are complex in nature.
• For a non elementary reaction, the order of reaction may be an integer or have a fractional value.
• example