Contextualization

Stoichiometry is one of the most vital topics in chemistry. It is the science that measures the quantitative proportions or relative masses of the chemical elements involved in a chemical reaction. These measurements have a variety of real-world applications, from the preparation of medications to rocket manufacturing. The central concept behind stoichiometry is the law of conservation of mass, which states that the total amount of mass in an isolated system remains constant, regardless of the chemical reactions that occur within that system.

A solid understanding of stoichiometry requires learning about the concepts of mole, molar mass, and molar volume. These concepts allow chemists to translate between the language of the macroscopic world (grams, liters) and the language of the atomic and molecular world (number of atoms, molecules). Using these concepts and the law of conservation of mass, it is possible to calculate the amount of reactants needed to produce a specific amount of product in a chemical reaction, or vice versa.

Stoichiometry has vital applications in many fields of science and engineering. In the chemical and pharmaceutical industry, stoichiometric calculations are used to determine the amount of reactants needed to produce a desired amount of product. In environmental science, stoichiometry helps understand biogeochemical cycles and interactions between organisms and their environment. In materials engineering, stoichiometry is essential for designing materials with desired properties.

We suggest the following reliable sources in Portuguese for further study:

• Book "Chemistry: The Central Science" by Theodore L. Brown, available at your school's library.
• Portal Brasil Escola, which provides a series of articles on stoichiometry, such as this link.
• Video lessons on Professor Paulo Valim's YouTube channel, focused on stoichiometry.

Practical Activity

Activity Title: "Formula Stocks"

Project Objective

This activity aims to calculate and analyze the basic stoichiometry of cooking chemical reactions. By the end of the project, students should be able to perform calculations of mass, volume, moles, etc., as well as have a deep understanding of the subject of stoichiometry.

Each group should consist of 3 to 5 students, and it is estimated that the project will take between two to four hours to be completed per participant. The deadline for project submission is one week.

Detailed Project Description

Students will select a cooking recipe of their choice that involves a chemical reaction, such as a cake or bread, and will perform stoichiometric calculations based on the provided ingredients and quantities. They will compare their theoretical predictions with the practical results obtained after preparing the recipe.

Required Materials

1. A cooking recipe chosen by the group that involves a chemical reaction.
2. Ingredients for the recipe.
3. Kitchen utensils necessary for recipe preparation.
4. Notebook and pen for recording observations and calculations.
5. Computer with Internet access.

Step by Step

1. Select a cooking recipe that involves a chemical reaction.
2. Analyze the recipe and identify the products and reactants involved and their quantities.
3. Perform stoichiometric calculations based on the quantities of reactants and products in the recipe. Predict the theoretical results of the reaction.
4. Prepare the recipe and observe the chemical reaction occur. Record your observations.
5. Compare the practical results with your theoretical predictions and discuss the differences.

Project Deliverables

At the end of this project, each group must deliver:

1. The selected recipe, with a clear explanation of the ingredients and quantities, as well as the preparation steps.
2. The report of stoichiometric calculations performed, including theoretical predictions and practical observations.
3. A written document in the form of a report containing:
   • Introduction: Provide context on the topic, its relevance and real-world applications as well as the application of this project.
   • Development: Explain the theory behind stoichiometry, detail the activity carried out, indicate the methodology used, and present and discuss the results obtained.
   • Conclusion: Summarize the main points, describe the learnings obtained, and draw conclusions about the project.
   • Bibliography: Indicate the sources used to carry out the project such as books, web pages, videos, etc.

The report should be digitally formatted, in a clear and concise manner, and include images, tables, or relevant graphics to represent the results in an understandable way.