CHM 2046C Module Nine Sample Exam

Part B: Factors Forming Rate Constant: k’ 10 points

In the Rate expression in Part A: Rate_INT = dP/dT = k’[A][B];

Is the rate constant k’ a number greater than one or less than one, why?

Has to be fraction so that when multiplied by the Product of the Reactant Concentration Terms, a number very large and greater than one, representing to total possible reaction pathways, the Actual Rate of the reaction is some value far less than the theoretical number of reaction pathways.

What does this number represent?

Rate Constant:

K’ = f ∙ e ^-Ea/RT ∙ o ∙ t

fraction x fraction x fraction x fraction = a very small fraction

The rate constant k’ can be broken down into the product of four factors. What are the four factors and what does each factor represent? Are each of these greater than one of less than one?

1) Frequency Factor f: The fraction of the total reaction pathways which actually collide during an interval of time! (usually per second)

2) Energy Factor:

The fraction of the colliding molecules which have sufficient energy to react! e^-Eact/RT

Energy of Activation:

3) Orientation Factor(o):

The fraction of the colliding molecules with sufficient energy to react, which are also properly orientated for reaction!

Transmission Coefficient (t):

A percentage of the colliding molecules with sufficient energy to react, which are also properly orientated for reaction, which do react (while the difference is a fraction of the colliding molecules properly orientated with sufficient energy to react which fail to react!)