Contextualization

Introduction

Our lives are filled with mixtures - the water we drink, the air we breathe, the food we eat, everything is the result of some type of mixture. In the realm of chemistry, there are two main types of mixtures - homogeneous and heterogeneous. Homogeneous mixtures are those in which we cannot distinguish its components, such as coffee with milk. In heterogeneous mixtures, we can easily identify the components, such as in a fruit salad.

Conceptually, we can understand that a mixture is a combination of two or more substances in which each one maintains its individual characteristics. In turn, these substances can be pure or already be mixtures. But how do we distinguish between different types of mixtures? What characteristics are relevant to this definition? These are some of the questions we want to answer in this project.

Contextualization

Understanding the types of mixtures is fundamental not only for the comprehension of chemistry but also for understanding various situations in our daily lives. When we prepare a natural juice, cook food, mix paints to paint a wall. Even the products we use to clean our house, in all these cases, we are dealing with different types of mixtures.

In a broader perspective, many industrial processes, such as the production of medicines, cosmetics and processed foods, depend on the understanding and the ability to create and manipulate different types of mixtures. Therefore, knowledge about mixtures has very broad practical applications, from our daily household chores to applications in industry and scientific research.

As a resource for study and deepening in the subject, we suggest the book by Professor Usberco and Salvador, "Química - Volume Único" (Editora Saraiva), chapters 14 and 15. For an online resource, we suggest the website SóQ (www.soq.com.br), which has a section dedicated to mixtures. In addition, explanatory videos can be a good way to visualize and better understand the concepts, we recommend the channel "Química em Ação" on YouTube.

Practical Activity

Activity Title: "Delving into Mixtures"

Project Objective

The objective of this project is to provide students with a hands-on experience of creating and analyzing different types of mixtures. Groups should:

• Prepare and classify different types of mixtures (homogeneous and heterogeneous);
• Identify the properties of the substances before and after mixing them;
• Perform the separation of mixtures using different methods.

Detailed Project Description

Each group of 3 to 5 students will have one month to conduct experiments with mixtures. They will be responsible for choosing the materials, making the mixtures, classifying them, analyzing their properties and, finally, trying to separate them using different methods that they will research.

Required Materials

• Materials for making mixtures (water, oil, salt, sand, sugar, alcohol, etc.)
• Transparent glass containers of various sizes
• Mixing spoons
• Coffee filter and funnel for filtration
• Scale to weigh the materials before and after mixing
• Stopwatch

Detailed Step-by-Step Activity

1. Make a work plan: First, the group should meet (virtually or in person) to discuss and plan the mixtures they want to make. The work plan should include the materials to be used, the types of mixtures to be made and the separation methods to be tested. This plan will be the roadmap of the project.

2. Preparation of mixtures: Using the chosen materials, students will prepare the mixtures following the work plan. They need to record every step, including the amount of each material used and the time for the mixture to stabilize.

3. Classification of mixtures: After preparation, students should observe and classify the mixtures as homogeneous or heterogeneous.

4. Analysis of properties: Students should observe and record the properties of the substances before and after mixing. This may include color, density, weight, among others.

5. Separation of mixtures: Using different methods researched, students should try to separate the mixtures and record the process and results.

6. Documentation: Students should document each step of the process, including the work plan, the preparation and classification of the mixtures, the analysis of the properties and the separation of the mixtures. In addition, they should compare the results obtained with the theoretical information researched.

Project Delivery

Upon completion of the practical component, each group will need to prepare a final report. This document should follow the following format:

1. Introduction: In this section, the group should provide an overview of the project, the objective and the relevance of the topic "Types of Mixtures" in the real world and in science.

2. Development: Here, the group should explain in detail the theory behind the topic, describe each step of the activity carried out, indicate the methodology used in practice, and present and discuss the results obtained.

3. Conclusion: Here, students should summarize the main points of the project, explain the lessons learned and the conclusions drawn about the project. This should include the effectiveness of the separation methods used and what was learned about the classification and properties of mixtures.

4. Bibliography: Finally, the group should list all sources consulted for the project, including books, web pages, videos, etc.

This project is an excellent opportunity to develop important technical skills, such as classifying mixtures and analyzing substances, but also socioemotional skills such as teamwork, time management, creative thinking and proactivity.