Introduction

Chemistry is a science that studies matter, its transformations, properties, and structures. One of the fundamental bases of chemistry is the study of ponderal laws, more specifically the Law of Lavoisier, also known as the law of conservation of matter. This law, formulated by the French chemist Antoine Lavoisier, states that in a chemical reaction that occurs in a closed system, the total mass of the reactants is equal to the total mass of the products. This means that matter is neither created nor destroyed during a chemical reaction, only transformed.

The Law of Lavoisier marked the beginning of modern chemistry and allowed for a greater understanding of the chemical processes that occur around us. This law made it possible to balance chemical equations, enabling more precise predictions about chemical reactions. This is essential both in research laboratories and in industries, where it is necessary to precisely quantify the substances involved in production processes.

Understanding the Law of Lavoisier is crucial for the comprehension of various other areas of chemistry and is an essential skill for those wishing to pursue a career in exact or biological sciences. A deep understanding of this law will allow the development of analytical skills and the ability to predict the behavior of different chemical systems.

Contextualization

The Law of Lavoisier applies not only in academic or industrial contexts but also in our daily lives, even if we do not realize it. For example, when cooking, the mass of the ingredients before cooking is the same after cooking, considering that all gases produced are kept in a closed system. Or in natural processes, such as photosynthesis, where the mass of plants (products) comes from the mass of carbon dioxide and water (reactants).

The importance of the Law of Conservation of Mass extends to environmental issues. For example, the notion that the mass of the waste produced by an industry must be equal to the mass of the inputs used allows us to track and quantify the pollution produced, assisting in the creation of sustainability policies.

To delve even further into this subject, we recommend the following sources:

1. Khan Academy: Law of Lavoisier

2. Manual do Mundo: Experiments on the Law of Lavoisier

3. Canal Física Total: Law of Lavoisier

Practical Activity: Demonstrating the Law of Lavoisier with Balloons

Project Objective

Validate the Law of Lavoisier through a hands-on and fun experiment.

Project Description

In this project, groups will carry out a simple experiment that explores the conservation of mass (Law of Lavoisier). Students will fill balloons with baking soda and vinegar, and measure the weight before and after the reaction to verify if the total mass remains the same - thus validating the Law of Lavoisier.

Each group should record their observations, discussions, and results in a final report that should follow the following format: Introduction, Development, Conclusions, and Bibliography used.

Necessary Materials

1. Balloons
2. Baking soda
3. Acetic acid (vinegar)
4. Empty plastic bottle
5. Precision scale
6. Funnel

Activity Step-by-Step

Preparation

1. Form groups of 3 to 5 people.
2. Each group should take a balloon and put about 2 tablespoons of baking soda inside it with the help of a funnel.

Experimentation

3. Weigh the balloon filled with baking soda and record this value.
4. Now, add approximately 100 mL of vinegar into the plastic bottle.
5. Weigh the bottle with vinegar, record this value.
6. Place the opening of the balloon filled with baking soda over the opening of the plastic bottle, so that the baking soda does not fall into the bottle.
7. Weigh the balloon + bottle assembly again (without the baking soda having reacted with the vinegar) and record this value.
8. Now, lift the balloon, allowing the baking soda to fall into the bottle and react with the vinegar.
9. Observe the balloon filling up with the carbon dioxide produced in the reaction.
10. When the reaction stops and the balloon stops inflating, weigh the balloon + bottle assembly again and record this value.

Discussion and Report Elaboration

Now, each group should gather their observations and results and discuss them in relation to the Law of Lavoisier.

The report should contain:

1. Introduction: Contextualize the theme, point out its relevance and application in the real world, and explain the objective of this project.
2. Development: Explain the Law of Lavoisier, the activity in detail, the methodology used, and finally present and discuss the results obtained.
3. Conclusion: Summarize the main points, the learnings obtained, and the conclusions drawn from the project.
4. Bibliography: Indicate the sources consulted for the project.

The expected duration of this project is two to four hours per student, and the deadline for submitting the report is one week after the experiment is conducted.