Vernier Software and Technology
Vernier Software & Technology

Rate Determination and Activation Energy

Introduction

An important part of the kinetic analysis of a chemical reaction is to determine the activation energy, Ea. Activation energy can be defined as the energy necessary to initiate an otherwise spontaneous chemical reaction so that it will continue to react without the need for additional energy. An example of activation energy is the combustion of paper. The reaction of cellulose and oxygen is spontaneous, but you need to initiate the combustion by adding activation energy from a lit match.

In this experiment you will investigate the reaction of crystal violet with sodium hydroxide. Crystal violet, in aqueous solution, is often used as an indicator in biochemical testing. The reaction of this organic molecule with sodium hydroxide can be simplified by abbreviating the chemical formula for crystal violet as CV.

{\text{C}}{{\text{V}}^{\text{ + }}}{\text{ }}{\text{(aq)  +  O}}{{\text{H}}^{\text{ - }}}{\text{ (aq)}} \to {\text{CVOH (aq)}}

As the reaction proceeds, the violet-colored CV+ reactant will slowly change to a colorless product, following the typical behavior of an indicator. You will measure the color change with a Vernier Colorimeter or a Vernier Spectrometer. You can assume that absorbance is directly proportional to the concentration of crystal violet according to Beer’s law.

The molar concentration of the sodium hydroxide, NaOH, solution will be much greater than the concentration of crystal violet. This ensures that the reaction, which is first order with respect to crystal violet, will be first order overall (with respect to all reactants) throughout the experiment. You will monitor the reaction at different temperatures, while keeping the initial concentrations of the reactants the same for each trial. In this way, you will observe and measure the effect of temperature change on the rate of the reaction. From this information you will be able to calculate the activation energy, Ea, or the reaction.

Objectives

In this experiment, you will

  • React solutions of crystal violet and sodium hydroxide at four different temperatures.
  • Measure and record the effect of temperature on the reaction rate and rate constant.
  • Calculate the activation energy, Ea, 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 »

Advanced Chemistry with Vernier

See other experiments from the lab book.

1The Determination of a Chemical Formula
2The Determination of the Percent Water in a Compound
3The Molar Mass of a Volatile Liquid
4Using Freezing-Point Depression to Find Molecular Weight
5The Molar Volume of a Gas
6Standardizing a Solution of Sodium Hydroxide
7Acid-Base Titration
8An Oxidation-Reduction Titration: The Reaction of Fe2+ and Ce4+
9Determining the Mole Ratios in a Chemical Reaction
10The Determination of an Equilibrium Constant
11Investigating Indicators
12The Decomposition of Hydrogen Peroxide
13Determining the Enthalpy of a Chemical Reaction
14ASeparation and Qualitative Analysis of Cations
14BSeparation and Qualitative Analysis of Anions
15AThe Synthesis of Alum
15BThe Analysis of Alum
16Conductimetric Titration and Gravimetric Determination of a Precipitate
17Determining the Concentration of a Solution: Beer's Law
18Liquid Chromatography
19Buffers
20Electrochemistry: Voltaic Cells
21Electroplating
22The Synthesis and Analysis of Aspirin
23Determining the Ksp of Calcium Hydroxide
24Determining Ka by the Half-Titration of a Weak Acid
25The Rate and Order of a Chemical Reaction
26The Enthalpy of Neutralization of Phosphoric Acid
27α, β, and γ
28Radiation Shielding
29The Base Hydrolysis of Ethyl Acetate
30Exploring the Properties of Gases
31Determining Avogadro's Number
32Potentiometric Titration of Hydrogen Peroxide
33Determining the Half-Life of an Isotope
34Vapor Pressure and Heat of Vaporization
35Rate Determination and Activation Energy

Experiment 35 from Advanced Chemistry with Vernier Lab Book

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

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