Answer to Question #154708 in Physical Chemistry for Wani

Question

Consider a general reaction between A and B which proceeds via a transition state, X≠:

  A+ B = X# - products

Calculate the frequency factor, A, for each of the following reactions at 207 oC using 

the transition state theory: 

(i) A reaction between two atoms, A and B, forming a diatomic transition state, X≠. 

(ii) A complex reaction between two non-linear molecules A and B forming a non-linear 

transition state, X≠ 

Assume qT = 108; qR =10; qV = 1

Answer 1

      Consider a general reaction between A and B which proceeds via a transition state, X≠:

 A+ B = X# - products

Calculate the frequency factor, A, for each of the following reactions at 207 oC using 

the transition state theory: 

(i) A reaction between two atoms, A and B, forming a diatomic transition state, X≠. 

(ii) A complex reaction between two non-linear molecules A and B forming a non-linear 

transition state, X≠ 

Assume qT = 108; qR =10; qV = 1

For simple reactions transition state can predict E and A in concert with computational chemistry. In transition state theory (TST) an activated molecule is formed during the reaction at the transition state between forming products from reactants.

                                                 

The rate of reaction is equal to the product of the frequency, v_I, of the activated complex crossing the barrier and the concentration of the transition state complex

                                                                 

The transition state molecule and the reactants are in pseudo equilibrium at the top of the energy barrier.

                                                                  

Combining

                                                             

We will now use statistical and quantum mechanics to evaluate  to arrive at the equation

                                                

where q¢ is overall the partition function per unit volume and is the product of translational, vibration, rotational and electric partition functions, i.e.,

                                                                

The individual partition functions to be evaluated are:

            Translation

                            

            Vibration

                                                            

                                          

            Rotation

                                    

                                                                   

                                                   for diatomic molecules

           The Eyring Equation

                       Liquids

                       Gases