Introduction and Context

Key Theoretical Concepts

Solutions

A solution is a homogeneous mixture of two or more substances. In this mixture, the solute is the substance present in smaller quantity and is dissolved by the solvent, the substance present in larger quantity. The result is a uniform mixture at a molecular level, meaning the different components of the solution cannot be distinguished by the naked eye.

Solute and Solvent

The solute is the substance that will be dissolved, while the solvent is the substance that will dissolve the solute. When we dissolve sugar in water, for example, sugar is our solute and water is the solvent.

Solution Concentration

The concentration of a solution is a measure of the amount of solute that is dissolved in a fixed amount of solvent. Concentrations can be expressed in various ways, including grams per liter, moles per liter, weight percentage, among others.

Context

Solutions are very actively present in our daily lives. In our diet, in the preparation of juices and cooking food, in industrialized beverages, in the manufacturing of medicines, and in many other examples. Understanding the process of solution and how we can alter its concentration is fundamental for our daily lives.

Moreover, the study of solutions is an essential part of exact and biological sciences, including chemistry, physics, biology, and medicine. Whether in the preparation of reagents for a chemical reaction, in the analysis of biological samples, or in the dosage of a medication, understanding the concentration and preparation of solutions is crucial.

Practical Activity

Activity Title: Mixing Solutions

Project Objective

The project aims to understand the influence of varying solute concentrations on the density of a solution, as well as to develop teamwork, communication, and time management skills.

Project Description

Teams of 3 to 5 students will create three salt solutions in water with different concentrations and then compare their densities. The result will be a deeper understanding of how the amount of solute in a solution affects its physical properties, such as density.

Required Materials

• Table salt
• Water
• Digital scale
• 100ml beaker
• 50ml graduated cylinders
• Pipette
• Stopwatch

Project Steps

Preparation of Solutions

1. Divide the group into three subgroups and assign each one the task of creating a salt solution in water with a different concentration (low, medium, and high).
2. Each subgroup should weigh the appropriate amount of salt and water to produce their solution.
3. Dissolve the salt in water, stirring well until no visible grains remain.
4. Repeat the steps for each subgroup.

Density Measurements

5. Each subgroup should now measure the density of their solution using the pipette and graduated cylinder.
6. Record the observations and results.

Analysis and Discussion

7. As a group, discuss the results. Does the density of the solution increase as the salt concentration increases? Why?
8. Prepare a report with your observations, analyses, and conclusions.

Project Deliverables

Groups must submit a report detailing the entire project implementation process, including the preparation of solutions, the measurement of their densities, the analysis of the results, as well as a discussion on the theoretical and practical implications of their findings.

The report should be subdivided into four main parts:

1. Introduction: Provide context on the topic and explain why it is important to understand solutions. Don't forget to indicate the objective of this project.
2. Development: Describe the theory behind solutions and density. Report the step-by-step activity, indicating the materials used, the methodology followed, and present the results obtained, explaining them according to the theory.
3. Conclusion: Based on your results and analyses, what have you learned about solutions? Does increasing the amount of solute increase the density of the solution? Justify. Also, reflect on what you learned in the teamwork process.
4. Bibliography: List the sources consulted to carry out the project and for the theoretical foundation.

The deadline for this project is one week. Take advantage of this activity to learn more about solutions and have fun!