## Drawing proposed structures for an activated complex

Arrhenius Equation: $\ln k = - \frac{E_{a}}{RT} + \ln A$

Glenda Marshall DIS 3M
Posts: 68
Joined: Sat Sep 27, 2014 3:00 am

### Drawing proposed structures for an activated complex

Can someone please explain how to draw a proposed stucture for an activated complex. Question #14.85 asks us to do this and I don't know where to start. The rate laws they gave are:

a) rate=k[CH3CHO] products are CH3 and CHO
b) rate=k[I]^2[Ar] products are I2 and Ar, the role of the Ar is to remove energy as the products are formed
c) rate=k[O2][NO2] products are NO2 and O

Thanks!

Sanmeet Atwal 1D
Posts: 17
Joined: Fri Sep 26, 2014 2:02 pm

### Re: Drawing proposed structures for an activated complex

Hi Glenda!
This is explained on page 72 of the course reader! But basically for part
a) you know that CH3CHO ---> CH3 + CHO so you know that the CH3CHO bond is breaking into CH3 and CHO and you would represent this by [CH3........CHO] to depict where the bond is breaking.
and you would do the same thing for parts b and c.
I'm not entirely sure but for part B i'm assuming you could write the rxn as 2I + Ar ----> I2 + Ar showing that the Ar doesn't bond to the 2I, instead it's there as an energy absorber (its also an inert gas so i'm pretty sure it wouldn't react).
So you would depict the two I molecules forming I2 as [I.....I.....Ar] showing where the bond between the two I molecules is forming and showing that Ar is present as an energy absorber.
Same thing for c) you know that 02 + NO ---> NO2 + O so you know that the O2 bond is breaking and an O molecule is forming a bond with the NO: [0....0....NO] The 0...0 depicts the 02 bond breaking and the 0....NO depicts the NO2 bond forming.

Hope this helps!!

Justin Le 2I
Posts: 142
Joined: Fri Sep 26, 2014 2:02 pm

### Re: Drawing proposed structures for an activated complex

It also helps to remember that activated complex diagrams are intended to show a middle transition phase. The reactants could continue to go on and form products (if they have enough energy and the right orientation) or go back and form reactants.

Glenda Marshall DIS 3M
Posts: 68
Joined: Sat Sep 27, 2014 3:00 am

### Re: Drawing proposed structures for an activated complex

Thank you Sanmeet! That was super helpful!