Objectives

Estimated time: (5 - 7 minutes)

Main Objectives:

1. Understand the concept and importance of chemical kinetics, and how it is essential to understand the speed of chemical reactions.
2. Identify and explain the main factors that influence the speed of a chemical reaction: temperature, concentration, pressure, and the presence of catalysts.
3. Apply the acquired knowledge to solve problems and practical situations related to chemical kinetics.

Secondary Objectives:

1. Develop research skills and autonomous learning, as students will be encouraged to seek information and learn about the topic before class.
2. Foster critical thinking and analytical skills, helping students understand how different factors can influence the speed of a chemical reaction.
3. Improve students' communication skills, as they will be encouraged to discuss and explain their understandings during class.

Introduction

Estimated time: (10 - 15 minutes)

• The teacher should start the class by reviewing the concept of chemical reactions, what reactants and products are, and the importance of understanding how these reactions occur. Examples of everyday chemical reactions can be used to illustrate the subject, such as the formation of rust, the burning of paper, or the effervescence of an effervescent tablet in water.

• Next, the teacher should propose two problem situations to arouse students' curiosity:

  1. Why does an egg cook faster in a pressure cooker?
  2. Why does the refrigerator preserve food better than leaving it at room temperature? These examples will lay the foundation for the discussion of the factors that affect the speed of chemical reactions.

• To contextualize the importance of the subject, the teacher can mention how chemical kinetics is important in various sectors of the industry, such as in the production of medicines, food, and fuels, where it is essential to understand and control the speed of chemical reactions to optimize these processes.

• To introduce the topic and capture students' attention, the teacher can share the following curiosities:

  1. The 1901 Nobel Prize in Chemistry was awarded to Jacobus H. van 't Hoff for his contributions to chemical kinetics. He demonstrated that the speed of a chemical reaction can be increased by raising the temperature.
  2. The reaction between baking soda and vinegar, known to many students due to the production of effervescent foam, is actually an excellent demonstration of the principles of chemical kinetics in action!

Development

Estimated time: (20 - 25 minutes)

Activity 1: Effervescent Reaction Experiment

1. Students will be divided into groups of three or four. Each group will receive a small bottle with a lid, an effervescent tablet, and a quantity of room temperature water.
2. The teacher should instruct the students to place the tablet inside the bottle, add the water, and quickly close the lid. They should observe the effervescent reaction that occurs and the pressure that forms inside the bottle.
3. It should be discussed that the observed effervescence is the result of a chemical reaction between the tablet and the water, and that the pressure that forms is due to the release of gas in this reaction.
4. Students should repeat the experiment, now with cold water and then with hot water, observing the differences in the reaction speed and the amount of pressure formed. They should record their observations.
5. The teacher should guide the discussion on how the water temperature affected the reaction speed, relating this observation to the concept of chemical kinetics.

Activity 2: Debate on the Use of Catalysts

1. After the experiment, the teacher should introduce the concept of catalysts and how they affect the speed of chemical reactions.
2. The teacher should then propose a debate among the groups on the ethics of using catalysts in different sectors, such as in the food and pharmaceutical industries. One group may argue in favor of using catalysts to increase efficiency and production, while the other may argue against their use due to possible side effects and environmental impacts.
3. Each group should have time to research and prepare their arguments, and then present them to the rest of the class.
4. After the presentations, the teacher should moderate a classroom discussion, allowing questions and comments.

Activity 3: Chemical Kinetics Problems Exercise

1. To consolidate the acquired knowledge, the teacher should distribute a set of problems involving chemical kinetics concepts. The problems should involve practical situations, such as determining the reaction speed under different temperature, concentration, and pressure conditions, or the effect of a catalyst.
2. Students should work in their groups to solve the problems, with the teacher circulating around the room to assist and clarify doubts.
3. After a set time, the teacher should call each group to present one of the solutions to the rest of the class, explaining the reasoning used. The teacher should then confirm the correct solution and explain any errors or misunderstood concepts.

Feedback

Estimated time: (8 - 10 minutes)

• The teacher should start the feedback phase by regrouping the class and conducting a discussion with all students about the solutions or conclusions found by each group. This is an opportunity for students to share their experiences, observations, and learnings with each other.

• The teacher should encourage students to make connections between the practical activities carried out and the theory presented at the beginning of the class. For example:

  1. How did the change in water temperature alter the speed of the effervescent reaction in the experiment?
  2. How can the use of catalysts be seen in the industries mentioned during the debate?
  3. How did the learned concepts help in solving the chemical kinetics problems?

• To promote deeper reflection, the teacher should suggest that students spend a minute silently thinking about the answers to the following questions:

  1. What was the most important concept you learned today?
  2. What questions still remain unanswered?

• After the minute of reflection, the teacher should open a space for students to share their answers with the class. This can provide the teacher with valuable feedback on which concepts need to be reviewed or reinforced in future classes.

• Finally, the teacher should end the class by summarizing the main points learned and reinforcing the importance of chemical kinetics in our daily lives and in various industries. The teacher may also provide additional materials for independent study to students, such as articles, videos, or websites related to the topic.

Conclusion

Estimated time: (5 - 7 minutes)

• The teacher should start the conclusion of the class by summarizing the main points covered and concepts learned during the class. This includes the definition of chemical kinetics, the factors that affect the speed of chemical reactions (temperature, concentration, pressure, and catalysts), and how these concepts were applied in practical situations during the activities.

• Next, the teacher should make a link between the presented theory, the practice carried out through the experiment, and the application of chemical kinetics concepts in everyday life and in various industry sectors. Highlighting how understanding these concepts allows not only to understand but also to control and optimize chemical reactions in different contexts.

• The teacher should then present some extra materials for students who wish to deepen their knowledge of chemical kinetics. These materials may include books, scientific articles, educational videos, and websites specialized in the subject. For example, the teacher may suggest reading an article on the application of chemical kinetics in the pharmaceutical industry, or watching a video on the influence of temperature on reaction speed.

• Finally, the teacher should reinforce the importance of the subject presented for students' daily lives and for society in general. For example, mentioning how chemical kinetics is present in natural processes such as food digestion and photosynthesis, in technologies such as refrigeration and fuel combustion, and in industrial sectors such as the production of medicines and food. This will motivate students to continue learning and applying chemical kinetics concepts in their lives.