Graphical Method to Determine Rate Orders:
Now that you understand how to use the initial rate method to determine a reaction's rate expression (k value and reactant orders), I want to show you a second way to determine a reaction's rate orders and rate constant (k). It relates the reactions concentration over the time of the reaction and uses a graphical method. View the video review this method.
Graphical Method (Integral Method)
More About Radiation:
Enjoy the videos!!!
Reaction Mechanisms:
Most reactions do not occur in one simple step. Typically, there are many elementary steps that add up to the overall reaction. These elementary steps are what we call the reaction's mechanism. The speed in which the reaction proceeds at (the reaction's rate) is soley determined by which of the elementary steps proceeds the slowest. When writing a rate expression for a reaction we are really writing the rate expression for the slowest step in the mechanism!!! The videos below are great resources to help you better apply the concepts of mechanisms and the rate determining step.
Reaction Mechanisms
Khan Academy Video (Click on the Title)
Non-First Step "Slow" Step Mechanisms:
What if the first step isn't the slow step in the mechanism? How can we determine the rate expression for the overall reaction? Due to an intermediate showing up in the slow step, we will have to find a method to substitute the rate at which the intermediate gets used up. This takes a little bit of clever substitution. The video below models this method and how you can determine the rate expression for these types of occurrences.