Examples A first order reaction has a rate constant of 1.00 s - 1 . For a first order reaction, and for a first order reaction only , the half life is a constant and is proportional to the inverse of the rate constant. For any order other than first order, the halflife of the reaction is dependent on the concentration. This is the appropriate units of a rate constant for a reaction that is third order overall.
All reactions are activated processes.
We know the rate constant for the reaction at two different temperatures and thus we can calculate the activation energy from the above relation. First, and always, convert all temperatures to Kelvin, an absolute temperature scale. Determine the order of this decomposition reaction. This is an initial rates problem. There is only one reactant, so our life is simple.