Determining the Rate Law from a Table
In order to determine the rate law for a chemical reaction one can use either the integrated rate law or the differential rate law. The integrated rate law is a mathematical expression that relates the concentration of a reactant over time. The differential rate law is an expression that relates the rate of change of a reactant’s concentration with respect to time. In order to determine the rate law from a table one must first determine the order of the reaction with respect to each reactant. The order of the reaction is the exponent to which the concentration of a reactant is raised in the rate law expression. For example if the order of the reaction with respect to reactant A is 2 then the rate law expression for the reaction would be:
rate = k[A]2
To determine the order of the reaction one can use the following method:
1) Calculate the initial rates of reaction for each set of experimental data. The initial rate of reaction is the rate of the reaction when the concentrations of all reactants are at their starting values.
2) Plot the experimental data on a graph with the concentration of one reactant on the x-axis and the initial rate of reaction on the y-axis.
3) Fit a line to the data. The slope of the line will be equal to the order of the reaction with respect to the reactant whose concentration is on the x-axis.
4) Repeat steps 2 and 3 for the other reactant.
5) Once the order of the reaction with respect to each reactant has been determined the rate law expression can be written.
What is the rate law?
The rate law is the equation that relates the rate of a reaction to the concentrations of the reactants.
What is the order of a reaction?
The order of a reaction is the sum of the powers to which the concentrations of the reactants are raised in the rate law expression.
How do you determine the order of a reaction from a rate law?
To determine the order of a reaction from a rate law you must take the logarithm of the rate law expression.
The order of the reactant will be the power to which its concentration is raised in the rate law expression.
What is the difference between a zero order reaction and a first order reaction?
A zero order reaction is one in which the rate is independent of the concentrations of the reactants.
A first order reaction is one in which the rate is proportional to the concentration of only one of the reactants.
How do you determine the rate law from a table of data?
To determine the rate law from a table of data you must first determine the order of the reaction.
Then you must find the rate constant by fitting the data to the rate law expression.
How do you determine the order of a reaction from a table of data?
To determine the order of a reaction from a table of data you must take the logarithm of the rate law expression.
The order of the reactant will be the power to which its concentration is raised in the rate law expression.
How do you determine the rate constant from a table of data?
To determine the rate constant from a table of data you must fit the data to the rate law expression.
What is the units of the rate constant?
The units of the rate constant depend on the order of the reaction.
For a zero order reaction the units are concentration^-1*time^-1.
For a first order reaction the units are time^-1.
What is the rate of a reaction?
The rate of a reaction is the change in the concentration of a reactant or product over time.
How do you determine the rate of a reaction from a table of data?
To determine the rate of a reaction from a table of data you must take the derivative of the concentration with respect to time.
What is the order of a reaction?
The order of a reaction is the sum of the powers to which the concentrations of the reactants are raised in the rate law expression.
What is the difference between a zero order reaction and a first order reaction?
A zero order reaction is one in which the rate is independent of the concentrations of the reactants.
A first order reaction is one in which the rate is proportional to the concentration of only one of the reactants.
How do you determine the rate law from a table of data?
To determine the rate law from a table of data you must first determine the order of the reaction.
Then you must find the rate constant by fitting the data to the rate law expression.
How do you determine the order of a reaction from a table of data?
To determine the order of a reaction from a table of data you must take the logarithm of the rate law expression.
The order of the reactant will be the power to which its concentration is raised in the rate law expression.
How do you determine the rate constant from a table of data?
To determine the rate constant from a table of data you must fit the data to the rate law expression.
