Contextualization

Stoichiometry is an important branch of chemistry that deals with the quantitative relationships between the substances involved in a chemical reaction. It is through stoichiometry that we can know, for example, how many moles of one substance react with how many moles of another substance, or how many grams of an element are needed to obtain a certain number of grams of a compound.

This concept is extremely useful in everyday life and industries. In cooking, for example, it is essential to know the exact amount of each ingredient to achieve the expected result. In the pharmaceutical industry, stoichiometry is used to calculate the amount of active ingredients needed to make different doses of a medication.

Introduction

Stoichiometry involves important concepts such as mole, molar mass, molar volume, stoichiometric coefficients, excess reagents, limiting reagents, etc. Throughout this project, we will delve into each of these concepts and learn how they relate to each other.

However, to better understand stoichiometry, it is important to first understand the Law of Conservation of Mass. According to this law, in a chemical reaction, the total mass of the reactants is equal to the total mass of the products. This means that if you start with 10 grams of reactants, you will end up with 10 grams of products. This is the basis for all stoichiometric calculations.

Another fundamental concept is the mole. The mole is a unit of measurement used in chemistry that represents a specific quantity of particles (such as atoms or molecules). One mole of any substance always has the same number of particles: 6.02 x 10^23, known as Avogadro's number. This concept is essential to understand the relationship between the mass of a substance and the number of particles it contains.

Practical Activity

Activity Title: "The Chemical Cupcake Factory!"

Project Objective

The objective of this project is to familiarize students with the concepts of stoichiometry, through the creation of their own "Chemical Cupcake Factory." In this activity, students will apply the concepts of stoichiometry, moles, molar mass, molar volume, among others, in the preparation of cupcakes.

Detailed Project Description

The groups, composed of 3 to 5 students, will have to create a cupcake recipe using common kitchen ingredients, applying the principles of stoichiometry. In addition, they will have to calculate the proportions of each component of the recipe based on stoichiometry to find the perfect amount of each ingredient they will use.

Required Materials

• Ingredients for the cupcake recipe (flour, sugar, eggs, butter, baking powder, etc.)
• Kitchen utensils (mixing bowl, spoon, cupcake pan, oven, etc.)
• Kitchen scale
• Calculator
• Notebook for notes
• Camera to document the process

Detailed Step-by-Step for Activity Execution

1. The groups should initially research a basic cupcake recipe and convert the measurements of the ingredients (e.g. cups, spoons, etc.) into grams, using the kitchen scale.

2. Next, they should calculate the molar mass of each ingredient and the number of moles they will use in the recipe. Assume that the molar mass of flour is 30 g/mol, sugar is 180 g/mol, egg is 60 g/mol, butter is 200 g/mol, and baking powder is 150 g/mol.

3. Based on the quantities of moles, they should adjust the quantities of the ingredients in the original recipe. For example, if the original recipe calls for 2 eggs (120 g) and they decide to use 1 mole of egg, they will need to adjust the amount of egg to 60 g.

4. After adjusting the quantities, they should prepare the recipe and bake the cupcakes.

5. Throughout the process, they should document all the steps, with photos and detailed notes on the quantities of each ingredient and the calculations performed.

6. Then, they should taste the cupcakes and evaluate. Were they good? Was the consistency good? Was the flavor balanced?

7. Finally, each group should write a report on the process, including all calculations and conclusions.

Project Deliverables

Students must submit a detailed report, properly illustrated with photos, which should contain the following topics:

1. Introduction: Contextualization of the theme, relevance and application of the same in the real world and project objective.

2. Development: Explanation of the theory behind the stoichiometric calculations performed, detailed description of the practical activity, methodology used, and presentation and discussion of the results obtained.

3. Conclusion: Recap of the main points, explanation of the learnings obtained, and conclusions drawn about the project.

4. Bibliography: Indication of the sources (books, websites, videos, etc.) used to develop the project.

This report should enrich the learning experience, not only demonstrating the technical knowledge acquired, but also reflecting on teamwork, problem-solving, and the applicability of stoichiometry in everyday situations.