To calculate average and relative reaction rates. You can measure the rate of a reaction, just like you can measure the speed a jogger runs. While a jogger would be reported to run a specific number of miles in an hour, miles/hour, a reaction is reported to form product or consume reagent in molar concentration per second, M/s. Reaction rate can be defined either as the increase in the concentration of a product per unit time or as the decrease of the concentration of a reactant per unit time. By definition, reaction rate is a positive quantity. In the reaction X→2Y, for example, Y is being produced twice as fast as X is consumed and thusrate of X=12(rate of Y)Each rate can be expressed as the change in concentration over the change in time? Δt:−Δ[X]Δt=12(Δ[Y]Δt)