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Give a detailed account of the collision theory of reaction rates of bimolecular gaseous reactions.

 Give a detailed account of the collision theory of reaction rates of bimolecular gaseous reactions.

Grade:11

2 Answers

BOLLU SRINIVAS
420 Points
8 years ago
This theory was proposed by Arrhenius and developed by Max Trautz & William Lewis to explain the rates of gaseous reactions.
¤ It is based on kinetic theory of gases.

¤ According to this theory the reactant molecules are assumed to be hard spheres.
¤ Collisions must takes place between reactants (molecules) to occur a reaction.
¤ Collisions are possible if 2 or more molecules are present.
¤ The minimum energy must be possessed by the reactant molecules to give
products is called threshold energy (ET).
¤ Molecules having other than threshold energy are called "normal molecules".
¤ Collisions between normal molecules are called "normal collisions", which
do not lead the chemical reaction, hence products are not formed.
¤ In addition to the normal molecules, the molecules must aquire some extra
amount of energy, called "activation energy" (Ea).
  
Ea = ET − ER
 
 
 
Niyazi Azam Khan
16 Points
5 years ago
*Reacting molecules are assumed to be spheres and reacting molecules shall have to collide to give products
*All collisions do not lead to formation of products
*The minimun energy required by the colliding molecules to give products is called Threshold energy.
*The additional energy supplied to reacting molecules ti reach threshold energy(ET)is called activation energy(Ea)
Ea=ET-ER (ER=Energy of normal molecules at S.T.P)
*The molecules which possess threshold energy are called activated molecules
*The activated molecules collide with each other and those collisions are called  activated collisions (or) Effective collisons
*Due to Effective collisions products are formed
*For Bimolecular elementary reaction
        A+B--->Products
        Rate expression(or)rate=ZAB.e-Ea/RT
          ZAB=Collision frequency of reactant A and B
        Ea
     -  ------ =Fraction of molecules with energies
       RT
equal (or) greater than activation energy
*Another factor 'P' is introduced for effective collisions w.r.t 'p' rate of reaction =PZAB.e-Ea/RT
     P=Probability factor(or)Steric factor
*A reaction takes place only when reactant molecules collide with proper orientations
*So in collision theory activation energy and proper orientation of molecules together determine the effictive collision.
*Eg:Formation of CH3OH forms CH3Br proper orientation of reactant molecules lead to bond formation improper orientation makes them simply bounce back and no products are formed..
  
 
       

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