Contextualization and Introduction

Chemical Kinetics is the branch of Chemistry that studies the speed of chemical reactions and the factors that influence them. This speed can be affected by various factors, such as the concentration of the reactants, the temperature at which the reaction occurs, the presence of catalysts, and, one of the most important, the Activation Energy.

Activation Energy, or Ea, is the minimum amount of energy that the reactants must have for the chemical reaction to occur. This means that the kinetic energy of the molecules must be equal to or greater than Ea for the reaction to take place. The way to calculate this is through the Arrhenius Equation, a mathematical equation that relates the activation energy to the speed of the chemical reaction.

By understanding how Activation Energy affects the speed of chemical reactions, it is possible to apply this knowledge to optimize industrial processes, predict the behavior of reactions, and even understand how biological processes work, since all these areas have chemical reactions occurring all the time.

In our daily lives, Chemical Kinetics and Activation Energy play fundamental roles. They are present in the reactions that occur in our bodies, in the formation of the foods we consume, in the development of medications, and in the planning of industrial processes. Understanding these concepts allows not only the optimization of these processes but also the search for more sustainable and efficient solutions.

Furthermore, the study of Activation Energy is multidisciplinary, involving concepts of Physics, such as energy and temperature, and mathematics, in the application of the Arrhenius equation. Therefore, this topic is more than just a Chemistry content. It is a practical example of how knowledge acquired in different disciplines connects and is applied in the real world.

This contextualization will help you in the initial stages of the project. As an additional research recommendation, I suggest reading the book 'Chemistry: The Central Science' by Brown, LeMay, and Bursten for a more in-depth review of the concepts of chemical kinetics and activation energy. Additionally, the website 'Tablet da Química' (link) offers a more didactic explanation of the subject. Finally, the YouTube channel 'Ciência em Ação' has a series of videos that bring concepts of chemical kinetics applied to real experiments.

Practical Activity

Activity Title:

Activation Energy in Everyday Life

Project Objective:

Understand and apply the concept of activation energy through the realization of a practical experiment, followed by the analysis and discussion of the results obtained.

Detailed Project Description:

Students, divided into groups of 3 to 5 members, will carry out a practical experiment with the aim of observing the effect of activation energy on different chemical reactions. The experiment will consist of comparing the decomposition rate of potassium permanganate (KMnO4) at different temperatures to observe how temperature (and consequently, activation energy) affects the reaction rate.

Students should then perform calculations to determine the activation energy for each of the observed reactions using the Arrhenius equation. The results obtained should be discussed and analyzed in relation to what was learned in theory about activation energy and chemical kinetics.

Required Materials:

• Potassium permanganate (KMnO4)
• Beaker
• Thermometer
• Stopwatch
• Matchstick or lighter
• Oven or heat source
• Analytical balance

Detailed Step-by-Step for Activity Execution:

1. Weigh a fixed amount (for example, 1g) of potassium permanganate in a beaker.
2. Heat the potassium permanganate to a fixed temperature (for example, 40ºC) using the oven or another heat source.
3. With the help of the thermometer, confirm that the potassium permanganate has reached the desired temperature.
4. Start the stopwatch and record the time it takes for the potassium permanganate to decompose completely.
5. Repeat steps 1 to 4 increasing the temperature of the potassium permanganate in 10ºC increments (for example, 50ºC, 60ºC, 70ºC, etc.).
6. Use the obtained data (decomposition time and temperature) to calculate the activation energy of the observed reactions using the Arrhenius equation.

Project Deliverables:

Students must submit a complete report detailing the entire process carried out and the learnings obtained. The report should include:

1. Introduction: The presentation of the topic, its relevance and application in everyday life, and the project's objective.
2. Development: A detailed description of the experiment performed, explaining the steps taken and the reason behind them. They should present and discuss the calculations performed and the results obtained, explaining the relationship between temperature and activation energy and how it affects the speed of the chemical reaction.
3. Conclusion: Review of the main points, conclusions drawn from the results, and the learnings obtained throughout the project.
4. Bibliography: Sources consulted for the project, correctly indicating the books, websites, or other means used.

This practical activity allows students to apply the theoretical concepts learned in a practical and engaging way, promoting collaboration and active learning. Additionally, the report forces students to organize their ideas in a rational and clear manner, training important skills in argumentation and scientific writing.

It is estimated that this activity will take approximately 15 to 20 hours to complete, including the time for preparation and execution of the experiment, analysis of the results, and the elaboration of the report.