So let's look at the following complex reaction in which two no molecules react with one BR two molecule to produce two moles of Nobr molecules. Now from experimental results we find that our rate law is k times concentration of no squared times the concentration of BR two squared. Now this guy comes from experiment and our goal in this lecture will be to find the rate law using the second step, the slow step and compare that rate law to our experimental rate law and see if they coincide. So first let's examine that situation at hand. Notice our first step is now the fast step and that means 1 mol of N o will react with 1 mol of BR two to produce 1 mol of no BR two. And this step will be really quick meaning that by the time it gets here it's going to go back.