Vernier Software and Technology
Vernier Software & Technology

The Rate and Order of a Chemical Reaction


A basic kinetic study of a chemical reaction often involves conducting the reaction at varying concentrations of reactants. In this way, you can determine the order of the reaction in each species, and determine a rate law expression. Once you select a reaction to examine, you must decide how to follow the reaction by measuring some parameter that changes regularly as time passes, such as temperature, pH, pressure, conductance, or absorbance of light.

In this experiment you will conduct the reaction between solutions of potassium iodide and iron (III) chloride. The reaction equation is shown below, in ionic form.

2{\text{ }}{{\text{I}}^{{\text{  -  }}}}{\text{(aq)   +   2 F}}{{\text{e}}^{{\text{3  +  }}}}{\text{(aq)}} \to {{\text{I}}_{\text{2}}}{\text{ (aq)   +   2 F}}{{\text{e}}^{{\text{2  +  }}}}{\text{(aq)}}

As this reaction proceeds, it undergoes a color change that can be precisely measured by a Vernier Colorimeter or a Vernier Spectrometer. By carefully varying the concentrations of the reactants, you will determine the effect each reactant has on the rate of the reaction, and consequently the order of the reaction. From this information, you will write a rate law expression for the reaction.


In this experiment, you will

  • Conduct the reaction of KI and FeCl3 using various concentrations of reactants.
  • Determine the order of the reaction in KI and FeCl3.
  • Determine the rate law expression for the reaction.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Option 1

Option 2

Option 3

Option 4

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Standards Correlations

See all standards correlations for Advanced Chemistry with Vernier »

Experiment 25 from Advanced Chemistry with Vernier Lab Book

<i>Advanced Chemistry with Vernier</i> book cover

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Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

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