The thing which got us started on this, however, was how to "fix" the rate law so that it could be used at different temperatures. One approach would be to use a graph like the one we've just seen to interpolate a value for the rate constant at a desired temperature. It is also possible to rewrite the equation in point-slope form (which eliminates the need to know the "constant"):

Now, if the activation energy is already known it is a "simple" matter to calculate a rate constant for a new temperature.

Finally, catalysts. Some substances have an unusual ability to increase the rates of some reactions without being used up. These substances are generally discovered by trial and error although in some cases what we learn about one catalyst may help us to "guess" what other substances might also work.