Contextualization

Theoretical Introduction

Common concentration or mass concentration is a key concept in chemistry that applies to solutions - homogeneous mixtures formed by two or more substances. Specifically, this concentration is a measure of the amount of a solute (dissolved substance) present in a certain volume of solution. It is usually expressed in grams of solute per liter of solution (g/L).

To better understand, imagine you have an orangeade - a mixture of orange juice (solute) and water (solvent). The common concentration of this juice would be the amount of orange juice (in grams) present in a liter of the orangeade.

Moving forward, it is also possible to calculate the concentration of various species in solution - for example, the amount of sugar or vitamin C in the orangeade. This allows us to compare the concentration of different orange juices or the efficiency of different juice extraction methods.

Contextualization

Common concentration is a widely used measure in many branches of science and industry. In medicine, for example, the concentration of different substances in the blood (such as glucose or cholesterol) is a crucial parameter for the diagnosis and monitoring of various diseases. In the food industry, the concentration of different components (such as sugars, proteins, etc.) is regularly measured for quality control.

But besides that, if you have ever made tea and added sugar, or prepared lemonade, you have already used the concept of common concentration, even without knowing it! The amount of tea or sugar you add to the water determines how strong or sweet the drink will be - in other words, its concentration.

Practical Activity

Activity Title: Common Concentration Laboratory - Investigating Common Beverages

Project Objective

This project aims to strengthen students' understanding of the concept of common concentration through a practical and playful activity. You will also develop skills such as teamwork, scientific reporting, time management, and research skills.

Detailed Activity Description

In groups of 3 to 5 students, each group will choose two different beverages: one light-colored and one dark-colored (for example, lemonade and coffee). You will prepare solutions of these beverages at various concentrations and then perform tests to determine which solution has the highest concentration. Next, you will present and discuss your results in a written report.

Required Materials

• Two different beverages (one light-colored, one dark-colored)
• Device for measuring volume (e.g., a graduated cylinder)
• Scale
• Glasses or glass containers
• Paper and pen for notes

Detailed Activity Steps

1. Choosing the Beverages: First, each group must choose the two beverages to be used in the experiment. They should be different in both color and composition.

2. Preparing the Solutions: After that, prepare three different solutions of each beverage, varying the amount of beverage (solute) in a certain volume of water (solvent).

3. Concentration Tests: Now it's time to determine which solution has the highest concentration. There are several ways to do this, and each group can choose the method they find most appropriate.

4. Data Recording: Throughout the experiment, do not forget to record all the data you obtained: the volumes and masses used, observations about the solutions, the results of the concentration tests, etc.

5. Writing the Report: Finally, each group must write a report on the experiment. This report should include all the sections described above: Introduction, Development, Conclusions, and Bibliography.

Project Deliverables

• Written Report: The report should follow the suggested format above, detailing all stages of the project, from choosing the beverages to conducting concentration tests and discussing the results. In the Conclusion, this report should indicate what was learned during the project, both in terms of scientific concepts and socio-emotional skills. The Bibliography should include all sources of information used during the project.

• Presentation of Results: In addition to the written report, each group must give a brief presentation (oral or slides) on the project to the class. This presentation should include the main points of the project and a discussion of the results.

The final deliverables of this project are directly connected to the activities suggested by promoting a theoretical-practical understanding of the concept of common concentration and developing interpersonal (teamwork, communication) and scientific skills (data recording, report writing).

Furthermore, by writing a report, it will reinforce the student's learning on the topic, as it will require them to explain the theory behind the central theme(s) of the project, explain the activity in detail, indicate the methodology used, and finally present and discuss the results obtained.

Writing the report will also teach them to organize information according to a logical flow and to write a technical document, important skills in many careers.