Project: Investigating Activation Energy

# Introduction

The study of chemical kinetics is one of the fundamental pillars for understanding the mechanisms of reaction and energy conversion in chemical processes. Specifically, activation energy is a fundamental concept for understanding how much energy is needed for a chemical reaction to occur and how this amount of energy can be modified, which is essential in areas such as the chemical industry, biochemistry, materials engineering, and more.

In simple terms, the activation energy is the minimum amount of energy that the reactant molecules must have for the chemical reaction to occur. Here, we learn to understand this energy consumed in the initial stages of a reaction where old molecular bonds are broken and new bonds are formed, and how we can calculate this energy using an equation called the Arrhenius equation.

Every chemical process that occurs around us has its own activation energy, and understanding this is important for controlling the rate of chemical reactions. Think of the flame of a lighter or match, for example: the activation energy here is the energy needed to initiate combustion. Or consider the process of cooking food: the activation energy is the energy needed to initiate the chemical reactions that transform raw food into cooked food.

Activation energy is also essential in the production of medicines, the control of chemical reactions in research laboratories, and the explanation of how enzymes work in living organisms. But it doesn't stop there; you will also use this concept in various other disciplines that involve chemical reactions, such as biology, chemical engineering, environmental science, and even in studies on global warming!

The sources suggested for the subject and further study of the concepts are:

1. Atkins, Peter; Jones, Loretta; Principles of Chemistry: questioning modern life and the environment. Bookman, 5th edition.
2. YouTube video "Activation Energy in Chemical Kinetics"
3. Chemistry Portal - Chemical Kinetics

# Hands-on Activity: Investigating Activation Energy

## Project Objective

To study and understand the concept of activation energy in chemical kinetics, especially how activation energy influences the rate of chemical reactions and how it can be changed by temperature.

## Project Description

This project will involve a series of simple experiments to explore the concept of activation energy. Students will carry out three experiments, measuring the rate of three different chemical reactions at different temperatures, in order to investigate the effect of temperature on activation energy and reaction rate. Students will work in groups of 3 to 5 and the project should take around two to four hours to complete.

## Materials Required

1. Thermometer
2. Stopwatch
3. Water (enough to fill three glasses)
4. Table salt
5. Sugar
6. Three clear glasses
7. Measuring spoons

## Step-by-Step

1. Fill three clear glasses with an equal amount of water, each at a different temperature: cold (iced), room temperature, and hot.

2. In the first glass (ice water), add a spoonful of salt and start timing how long it takes for the salt to completely dissolve, stirring the solution continuously.

3. Repeat Step 2 with the second glass (room temperature water) and the third glass (hot water).

4. Note down the times for each temperature.

5. Now repeat the experiment with sugar in each of the three glasses.

6. Compare the results obtained and discuss the influence of temperature on the rate of dissolution of salt and sugar.

7. Conclude on the influence of temperature on activation energy.

## Project Submission and Written Document

As the project is completed, students should produce a well-structured group report that contains:

• Introduction: Contextualize the concept of activation energy, the Arrhenius equation, and explain the objective of the project.

• Development: Describe the theory behind the proposed experiment, explaining the relationship between activation energy and temperature. Describe the methodology used (the experiments carried out), present, and discuss the results obtained.

• Conclusion: Conclude the work by summarizing your main points, and making explicit the lessons learned and conclusions drawn from the project. Relate the results to the concept of activation energy and the influence of temperature on the rate of chemical reactions.

• Bibliography: List the sources consulted during the project.

This report must be submitted one week after the start date of the project.