Differential rate equations shows the dependence of rate on concentration and the experimentally-determined exponents on the concentrations are the reaction order.
The integrated rate equation shows the dependence of concentration on time.
This activity is concerned with the integrated rate equations for reactions that are first or zero order in a particular reactant. Having completed the activity, you should be able to
The order of the reaction in the reactants give scientists important clues about the pathway of the reaction (the bond-breaking and bond-making steps that lead from reactants to products).
| differential rate equation | |
| zero order | |
| reaction rate = – | Δ[A] |
| Δt | |
| first order | |
| reaction rate = – | Δ[A] |
| Δt | |
| integrated rate equation | linear graph |
| zero order | |
| [A] = -kt + [A]0 |  |
| first order | |
| ln [A] = -kt + ln [A]0 |  |
The integrated rate equation shows the dependence of concentration on time.
Measuring changes in concentration is experimentally more straight-forward than measuring rate. Because the form of the integrated rate equation depends on the order of the reaction in the reactant being measured, the nature of the experimental dependence of concentration on time can be used to determine the order of the reaction in that reactant
This activity is concerned with the integrated rate equations for reactions that are first or zero order in a particular reactant. Having completed the activity, you should be able to
- describe the mathematical relationship of concentration of substance and time for reactions where the order of the reaction in the substance is either zero or one
- describe how the order of the reaction can be determined using a graph of an appropriate function of concentration against time and how the rate constant for the reaction can be determined from this graph
- describe how the length of sequential half lives depends on the order of the reaction
- calculate the half life and rate constant for a zero order or first order reaction from appropriate data
- calculate the concentration at a given time given appropriate information
- calculate the time taken for a particular change in concentration given the appropriate information