Contextualization

Internal Energy is a key concept in thermodynamics that refers to the total energy of a system, including the translational, rotational, and vibrational movements of molecules, as well as the electrical potential energy that exists between the molecules. The internal energy state of a system is closely related to its temperature, volume, and pressure, and it can be said to be an indicator of the 'agitation state' of the system's molecules.

Internal Energy is a fundamental concept in thermodynamics. Thermodynamics is the study of how energy is converted from one form to another. It is the branch of physics that explains how and why energy is transferred during a change of state. For example, when a gas expands and performs work against its surroundings, the internal energy of the gas decreases.

This area of knowledge is not only theoretical but has significant practical implications in our daily lives and in various industrial areas. For example, the operation of thermal machines, such as car engines and power plant turbines, depends on the thermodynamic principles related to internal energy.

Introduction

Internally, from a chemical point of view, has to do with the energy contained in the chemical bonds of molecules and the forces between them. This energy can be altered through chemical reactions, heat transfer, or work done on the system.

In Chemistry, internal energy is a key piece for understanding chemical reactions, as it helps predict whether a given reaction will release or absorb energy and in what quantity. This is crucial for understanding and manufacturing materials and energy production.

The resources we suggest for a deeper dive into the topic are:

• Khan Academy: Thermodynamics Section
• Book Chemistry: The Central Science, by Brown, LeMay, and Bursten
• YouTube Channel Ciência-Tec: Videos on Internal Energy and Thermodynamics

These resources offer a variety of texts, videos, and exercises to help understand and practice the concepts of Internal Energy.

Practical Activity

Activity Title: 'Internal Energy: Analysis of Chemical Reactions'

Project Objective:

This project aims to deepen students' understanding of the concept of internal energy and its relationship with chemical reactions.

Students will study, analyze, and represent chemical reactions, exploring how they alter the internal energy of a system and what the practical implications of these transformations are. Additionally, they should apply their findings in a real-world context, encouraging interaction, teamwork, and critical thinking.

Detailed Project Description:

Groups should choose two different chemical reactions and analyze the variation of internal energy in each. They should investigate whether the chosen reactions are exothermic or endothermic and use the energy conservation equation to calculate the variation of internal energy.

After the analysis, groups should produce a detailed report and present their findings to the class.

Finally, groups should suggest a practical application for the studied reactions, considering scientific, technological, and socio-environmental aspects.

Required Materials:

1. Textbooks and online materials for research.
2. Paper and pen for notes.
3. Presentation software (Microsoft PowerPoint, Google Slides, etc.)

Detailed Step-by-Step for Activity Execution:

1. Organize students into groups of 3 to 5 people.
2. Each group should choose two chemical reactions to analyze.
3. Students should research and study the chosen reactions, whether they are exothermic or endothermic, and learn how to calculate internal energy in each of them.
4. Using the energy conservation equation and the collected data, groups should calculate the variation of internal energy in the reactions.
5. Groups should create a presentation to share their findings with the class.
6. Finally, groups should suggest a practical application for the studied reactions and discuss this application considering scientific, technological, and socio-environmental aspects.

Groups will have one month to complete the project, with an estimated five to ten hours of work per student.

Project Delivery

Students should produce a detailed report containing the following main topics:

1. Introduction: Provide context for the study topic, the relevance of internal energy, and the project's objective.
2. Development: Explain the theory behind internal energy and the studied chemical reactions, detail the activities carried out, the methodology used, and present the results obtained.
3. Conclusions: Summarize the main points, present the learnings obtained, and the conclusions drawn from the project.
4. Bibliography: List all sources used for research and study.

The report will be a valuable document to demonstrate the group's understanding of internal energy, showcase the acquired knowledge, and reflections on the practical implications of internal energy in chemical reactions.