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. Now, we're only going to worry about the forward reaction, but know that if there is a forward reaction, there could also be a reverse reaction. Now let's look at the rate law. The rate law is this entire equation or relation.