Now, as long as the concentration of this guy is kept relatively low, we can approximate using these formulas here. So likewise, the rate of change or disappearance of A and B can be given by negative change in concentration of B divided by T. Now that only works if that intermediate concentration is kept low. Now let's talk about the rate law. The rate law is a mathematical representation that summarizes relationship between reactants and reaction rate. And it also builds a relationship between our rate constant and our rate of reaction. Now notice in this reaction we have a forward reaction and a reverse reaction.