Contextualization

Chemistry plays an important role in understanding the world around us. It is involved in everything, from the food we eat to the technology we use daily. Within these applications, the concepts of chemical equilibrium and partial pressures play a crucial role. These concepts allow predicting the behavior of a specific chemical reaction and are therefore fundamental to many areas, including pharmaceuticals, agribusiness, fuels, and many others.

One of the key concepts in chemistry is chemical equilibrium. It is important to understand that in a system at equilibrium, the concentrations of reactants and products do not need to be equal, but rather the concentrations remain constant. Additionally, we have partial pressures, which represent the contribution of an individual gas to the total pressure of the gas mixture. These pressures are intrinsically linked to chemical equilibrium when dealing with gases.

Introduction

Dalton's Law of Partial Pressures is one of the many practical applications of the concept of chemical equilibrium. This law states that the total pressure of a gas mixture is the sum of the partial pressures of all gases composing the mixture. In other words, each gas behaves as if it were the only one present and exerts a pressure that would be exerted if it occupied the same volume alone.

Associated with these partial pressures, we have Kp, the equilibrium constant for partial pressures. It represents the relationship between the pressures of the gases in a reaction at equilibrium. Kp is calculated in a very similar way to Kc (equilibrium constant in terms of concentration), but using partial pressures instead of gas concentrations.

In this project, you will have the opportunity to deepen your knowledge of chemical equilibrium and partial pressures, developing important technical and socio-emotional skills.

Suggested resources to deepen the topic and base the discussion:

1. Khan Academy: Chemical Equilibrium and Partial Pressures
2. Manual da Química: Chemical Equilibrium
3. Brasil Escola: Constancy of Partial Pressures

Practical Activity

Activity Title: "Getting the Pressure Right: A Study of Equilibrium and Partial Pressures"

Project Objective:

To develop a practical understanding of the concepts of chemical equilibrium and partial pressures through the simulation of a chemical reaction.

Detailed Project Description:

Students will simulate a chemical reaction in a closed system, monitoring changes in the partial pressures of the involved gases and the equilibrium of the reaction. The activity will be carried out in groups of 3 to 5 students, with an estimated duration of two to four hours.

Required Materials:

1. Balloons of different colors (to represent different gases)
2. Tape measure
3. Notebook for notes

Detailed Step-by-Step for Activity Execution:

1. The chosen chemical reaction should be simple and involve the transformation of one gas into another. For example, we can use the decomposition of hydrogen peroxide into water and oxygen.
2. Initially, students will simulate this reaction using balloons. A balloon of a certain color can represent hydrogen peroxide, while balloons of another color represent water and oxygen.
3. Students will inflate a certain number of balloons to represent the initial molecules of hydrogen peroxide. Measuring the circumference of the balloons (using the tape measure) will simulate the partial pressure of this gas.
4. Over time, students will "decompose" the hydrogen peroxide, emptying the balloon representing it and inflating balloons of other colors to represent water and oxygen. They will measure the circumference of the new balloons again to calculate the partial pressures.
5. During the simulation, students should record pressure changes and the number of balloons of each color in their notebook.
6. Students should then try to reach a state of equilibrium, where the decomposition of hydrogen peroxide and the formation of water and oxygen occur at the same rate. They will know they have reached equilibrium when the partial pressures of the gases remain constant.
7. After reaching equilibrium, students should explain their processes and observations, relating their results from the simulation to the theoretical concepts of chemical equilibrium and partial pressures.

Project Deliverables and Writing of the Written Document:

After completing the practical activity, each group should prepare a report document, with the following topics:

1. Introduction: Students should contextualize the theme, its relevance and application in the real world, as well as the objective of this project.
2. Development: Students should explain the theory behind chemical equilibrium and partial pressures, describe the activity performed in detail, indicate the methodology used, and finally present and discuss the results obtained in the simulation.
3. Conclusion: Students should conclude the work by summarizing its main points, explaining the learnings obtained, and drawing conclusions about the project.
4. Bibliography: Students should indicate the sources they relied on to work on the project such as books, web pages, videos, etc.

The document should be well-structured and fluent, demonstrating the correct use of technical vocabulary and the proper interpretation of experimental results.