In that case, we have to determine the rate law experimentally. But if we have a single step reaction, then we can use the coefficients to calculate the rate law. So in this particular case, going from A to B, a is the reactant and B is the product. And let's suppose the rate constant is k one and that means the rate law for this reaction is given by so the rate of the four reaction v forward is equal to k one multiplied by the concentration of A to the power of one, because the coefficient here is one. If this coefficient was two, then this exponent here would be two and so forth. Now, if we go in reverse, then the only thing that changes is this becomes the reactor, this becomes the product.