Context and Introduction:

Stoichiometry is an essential tool in chemistry that allows us to relate quantities of reactants and products in a chemical reaction. It is based on the law of conservation of mass, where the total mass of the reactants is equal to the total mass of the products in any chemical process. This law was established by the chemist Antoine Laurent Lavoisier in the 18th century and gave rise to the principle that 'in nature nothing is created, nothing is lost, everything is transformed'.

Stoichiometry is applied to determine the quantities of reactants needed and the products that can be formed during a chemical reaction. It involves the study of the quantitative relationship between substances in chemical reactions. The term 'stoichiometry' comes from Greek and means 'measuring elements'. By using the coefficients of balanced chemical equations, we can calculate the amount of reactants needed to produce a certain amount of products, or vice versa.

In our daily world, stoichiometry is fundamental. For example, in cooking, when we follow a recipe and measure the amount of ingredients needed to make a dish, we are practicing stoichiometry. In an industrial context, stoichiometry is used to determine the exact amounts of reactants needed to produce a specific amount of product, maximizing efficiency and minimizing waste. In medicine, pharmacists use stoichiometry to determine the appropriate doses of medications to be administered to patients.

In this project, we will explore stoichiometry in a fun and interactive way. We will use examples from our daily lives to solidify the concept of stoichiometry and understand its application in the real world.

Practical Activity: 'Stoichiometric Kitchen'

Project Objective

The objective of this project is to apply the concepts of stoichiometry in the context of cooking, enhancing students' understanding of molar balance in chemical reactions. Students will also have the opportunity to develop important practical skills, such as precise measurement of ingredients, performing simple mathematical calculations, and following a process from start to finish.

Project Description

In this project, students, grouped in 3 to 5 members, will be tasked with preparing, measuring, and baking cookies according to a provided recipe, making adjustments to the quantity of ingredients using the principles of stoichiometry.

Required Materials

1. Ingredients for the cookie recipe (flour, sugar, butter, eggs, baking powder, etc.)
2. Kitchen utensils (bowls, measuring spoons, kitchen scale, baking sheet, etc.)
3. Recording device (phone, camera, etc.)
4. Computer or notebook for the elaboration of the final report

Project Step by Step

Step 1: Preparation

Research and choose a simple cookie recipe. Translate the recipe into a 'chemical equation', where the ingredients are the 'reactants' and the cookies are the 'products'. Make sure all group members understand the recipe and how it relates to stoichiometry.

Step 2: Cooking with Stoichiometry

Bake the cookies according to the recipe. While doing so, make stoichiometric adjustments to the recipe. For example, if the original recipe makes 12 cookies and your group wants to make 24, calculate the necessary amount of each ingredient.

Step 3: Records

Record the calculations you made to adjust the recipe. Take photos or videos of the cooking process to include in your final report.

Step 4: Writing the Report

Each group should then write a detailed report on the project.

• In the Introduction, explain the concept of stoichiometry and its relation to the activity performed.
• In the Development, explain the process used to translate the recipe into the language of chemistry and how you performed stoichiometric calculations to adjust the recipe. Include the photos or videos taken during the activity.
• In the Conclusion, discuss what you learned from the activity, what the difficulties were, and how they were overcome.
• In the Bibliography, list all sources consulted during the project, whether for understanding the concept of stoichiometry or for practice in the kitchen.

Project Deliverables

Groups must submit a final written report with the required sections (Introduction, Development, Conclusions, and Bibliography) along with an appendix with photos or videos of the cooking process.

The purpose of the written document is to connect what was worked on in the kitchen practice with the concept of stoichiometry. The written part serves to formalize students' understanding of molecular relationships in a chemical reaction and enhance students' scientific communication skills.