Question

How to determine order of a two step reaction?

Answer 1

1
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1
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3 How to Determine Order of Reaction
Knowing how different concentrations of chemicals influence the speed of a reaction is imperative for many chemical processes. The term ‘reaction order’ (or order of reaction) refers to how the concentration of one or more reactants (chemicals) affects the rate of the reaction. The overall order of any reaction is the sum of the order of all present reactants. Though looking at a balanced chemical equation will not help you determine the order of the reaction, you can gain this information by looking at the rate equation or graphing the reaction in question.
Method One of Three:
Analyzing the Rate Equation
Identify the rate equation from the reaction. Only the rate equation can help you determine the order of the reaction. This equation shows the increase or decrease of a particular substance with respect to time. Other equations related to the chemical reaction will not help you identify the order of the reaction.[1]
Identify the order of each reactant. Each reactant listed in the rate equation will have an exponent of either 0, 1, or 2 (above 2 is very rare). That exponent denotes the order of that reactant. Looking at each exponent: [2]
A zero means that the concentration for that reactant has no bearing on the rate of reaction.
A one means that increasing the concentration of this reactant will increase the rate of the reaction in a linear way (doubling the reactant doubles the rate).
A two means that the rate of the reaction will increase by the square of the increased concentration (doubling the reactant will increase the rate by four times).
Zero order reactants are often not listed in the rate equation, since any number to the zeroth power is equal to one.