What are the methods used to determine reaction order?

There are several ways to determine reaction order.  

1. One method is the initial rate method. This method involves measuring the initial rates of the reaction at different initial concentrations of reactants. By plotting the initial rate versus the initial concentration of reactants, the reaction order can be determined. 
2. Another method is the graphical method. This method relies on concentration-time graphs of reactants. A series of standard solutions is used to create a Beer's Law plot, which establishes a relationship between absorbance and concentration. Three different graphs are then made. The first graph depicts the concentration of the isolated reactant against time. The second graph displays the inverse concentration plotted against time, while the third graph shows the natural logarithm of concentration versus time. Each graph corresponds to a potential reaction order: zero, first, and second order, respectively. The most linear graph reflects the reaction's order with respect to that reactant. 
3. A third method is the integrated rate law method. By integrating the rate law expression for a reaction, different integrated rate laws can be derived depending on the reaction order. Experimental data obtained from monitoring the concentration of reactants over time can then be fitted to these integrated rate laws. 
4. Another method is the half-life method. For reactions with known orders, the half-life of the reaction can be measured experimentally at different initial concentrations of reactants. Plotting the half-life versus the initial concentration allows for the determination of the reaction order.