Contextualization

Theoretical Introduction

Dilution is a chemical process that involves decreasing the concentration of a solute in a solution. This reduction is done by adding more solvent to the solution, which increases the total volume of the solution but keeps the amount of solute constant. This is an extremely important concept because it is routinely used both in industry and in everyday life.

The calculation of dilution is based on the law of conservation of mass, which states that the mass of the solute before dilution is equal to the mass of the solute after dilution. The mathematical formula for dilution is C1 x V1 = C2 x V2, where C1 and C2 are the concentrations of the solute before and after dilution respectively, and V1 and V2 are the volumes of the solvent before and after dilution respectively.

However, dilution is not limited to chemistry and the calculation of the concentration of solutions. It also has applications in areas such as microbiology (in the culturing of bacteria), pharmacology (in the preparation of medicines), and ecology (in the study of water and air pollution).

Contextualization of the Theme

The process of dilution is a key concept in the chemical, physical, and biological sciences. In chemistry, it is a fundamental component of laboratory experiments, as it allows scientists to work with manageable and safe concentrations of substances. In physics, dilution is a critical feature of processes such as heat transfer and electrical conduction.

In everyday life, dilution is a common process that we often carry out without realizing it. When we add water to concentrated juice or coffee, we are applying the concept of dilution. In medicine, drugs are often diluted to achieve the proper dose for the patient. In the environment, dilution plays a role in the dispersion of pollutants, which can both decrease and increase their potential impacts.

Practical Activity

Activity Title: Dilution "In Practice" and Its Impacts

Project Objective

This activity aims to enhance students' understanding of the concept and calculations of dilution and to apply them to a real-world situation. Additionally, students will develop teamwork, organization, documentation, and experiment reporting skills.

Detailed Project Description

The project will be carried out by teams of 3 to 5 students and will have a total duration of approximately 12 hours per student. It will be divided into two major stages: the planning and execution of a dilution experiment, followed by the application of the dilution concept in a real case.

Planning and Execution of the Experiment

The objective of this stage is for students to apply their knowledge of dilution in practice. They will need to plan and conduct an experiment in which they will dilute a food coloring solution in water and measure the concentration of the dye after each dilution.

Required Materials

• Food coloring
• Water
• Test tubes or measuring cups
• Spatulas or pipettes
• White paper
• Digital camera or smartphone

Detailed Step-by-Step

1. Plan the experiment, including how many dilutions will be made and what volumes of dye and water will be used in each dilution.
2. Carry out the experiment, keeping detailed notes of the entire process.
3. After each dilution, place a drop of the diluted solution on a white paper and take a picture with the camera or smartphone.
4. Use the photos to visually assess the change in the concentration of the dye at each dilution.

Application of the Dilution Concept to a Real Case

The objective of this stage is for students to apply their knowledge of dilution to a real-world situation. They will need to select a real case where dilution is relevant (it could be a case related to pharmacology, ecology, industrial chemistry, among others) and develop an analysis using the concepts of dilution.

Detailed Step-by-Step

1. Select a real case where dilution is relevant.
2. Research information about the case, including how dilution is applied in that context, how the dilutions are calculated, what the results of the dilutions are, etc.
3. Record a video explaining the selected case and how dilution is used in it.

Project Deliverables

At the end of the project, each group must submit:

1. A written report detailing the experiment, including the planning, execution, results, and analysis of the results. The report should follow the format of Introduction, Development, Conclusions, and Bibliography.

   • In the introduction, students should contextualize the theme, explain its relevance, and the objective of the project.

   • In the development, the theory of dilution should be explained, the experiment should be detailed, the methodology used should be presented, and the results obtained should be discussed.

   • In the conclusion, the main points should be summarized, the lessons learned should be stated, and the conclusions drawn about the project.

   • Finally, the bibliography used should be indicated.

2. A video explaining the selected real case and how dilution is used in it. The video should be clear, informative, and present a relevant analysis based on the concepts of dilution.