Lesson Plan | Active Learning | Concentration Units: Molarity

Assumptions: This Active Lesson Plan assumes: a 100-minute class, prior student study with both the Book and the start of Project development, and that only one activity (among the three suggested) will be chosen to be conducted during the class, as each activity is designed to take up a significant portion of the available time.

Objectives

Duration: (5 - 10 minutes)

This stage of the lesson plan aims to establish clear and specific objectives that will guide the activities of students and the teacher during the class. By clearly defining what is expected to be achieved, students can focus their learning efforts on the essential skills of calculation and understanding of molarity, which are crucial for the study and practice of Chemistry.

Main Objectives:

1. Enable students to calculate the molarity of a chemical solution using the mathematical formula molarity (M) = n/V, where n is the number of moles of solute and V is the volume of the solution in liters.

2. Develop skills in manipulating formulas and units of measurement to solve practical problems involving the preparation and dilution of solutions with different concentrations.

Side Objectives:

1. Encourage the application of the concept of molarity in real and everyday contexts, such as the preparation of solutions in laboratories or in the industry.

Introduction

Duration: (15 - 20 minutes)

The introduction aims to engage students with the theme of the class through problem situations that simulate real challenges and contextualizations that show the relevance of studying molarity for practical applications. This approach not only sparks students' interest but also prepares them to apply their prior knowledge critically and reflectively during practical activities in class.

Problem-Based Situations

1. Imagine you are a chemist responsible for preparing a hydrochloric acid solution for an experiment. The teacher provides you with a bottle containing 37% HCl by mass and asks you to prepare 500 mL of a 1M hydrochloric acid solution. How would you calculate the necessary amount of HCl and what procedures would you follow?

2. In a laboratory, you are tasked with preparing 250 mL of a 0.5M copper sulfate (CuSO4) solution. The copper sulfate you have available is a 1M solution. How would you dilute this solution to obtain the desired concentration?

Contextualization

Molarity is a unit of concentration widely used in various contexts, from research laboratories to the pharmaceutical industry. For example, in medicine, many intravenous treatments are administered in solutions with controlled molarity, ensuring the effectiveness and safety of patients. Additionally, understanding and knowing how to calculate molarity is crucial for chemistry students, as it forms the basis for many other units of concentration and chemical reactions.

Development

Duration: (70 - 80 minutes)

The development stage is designed to allow students to apply the concepts of molarity they have previously studied in a practical and interactive way. Through playful and challenging activities, students can consolidate their learning, developing calculation and problem-solving skills in a context that simulates real situations. The choice of an activity among the proposals aims to provide a differentiated learning experience, adapted to the teaching and learning style of the group, encouraging active participation and engagement with the content.

Activity Suggestions

It is recommended to carry out only one of the suggested activities

Activity 1 - The Master of Molarities

> Duration: (60 - 70 minutes)

- Objective: Develop skills in calculating molarity and manipulating solutions in a practical and collaborative context.

- Description: In this activity, students will be divided into groups of up to 5 people to solve a series of challenges involving the calculation and manipulation of molarities. Each group will receive a set of cards, each representing a component of a chemical solution (solutes and solvents) and their respective molarities and volumes. The goal is for students, using the molarity formulas, to prepare solutions with specific concentrations, following the instructions on the cards, and then use these solutions to perform a simple chemical reaction.

- Instructions:

• Divide the class into groups of up to 5 students.

• Distribute a set of cards to each group, each card representing a component of a chemical solution with its molarity and volume.

• Ask students to calculate the amount of solute needed to prepare a solution with a specific molarity and prepare the solution.

• After preparing the solutions, ask each group to perform a simple chemical reaction which should be recorded in a report.

• Each group will present their report and explain the process of calculating and preparing the solutions.

Activity 2 - Molarity Festival

> Duration: (60 - 70 minutes)

- Objective: Practice calculating molarity in a playful and interactive setting, encouraging critical thinking and problem-solving.

- Description: Students will participate in a festival where each booth represents a different type of solution (acids, bases, salts, etc.), each with a specific molarity. Students, organized in groups, will visit each booth, calculate the molarity of an unknown solution and conduct a simple chemical test to verify the accuracy of the calculation.

- Instructions:

• Prepare booths with solutions of different molarities and organize students into groups.

• Each group visits one booth at a time, where they receive a description of the solution components and the volume, but not the molarity.

• Students should calculate the molarity of the solution and test it with a chemical indicator or another simple method.

• After each test, students record the calculated molarity and the observed reaction.

• At the end, they discuss the differences between the calculated molarities and the actual ones, if known.

Activity 3 - Molarity Mission: The Rescue of the Missing Scientist

> Duration: (60 - 70 minutes)

- Objective: Encourage teamwork and the practical application of the concept of molarity in a scenario that involves logical reasoning and deduction.

- Description: In an atmosphere of mystery and challenge, students will have to solve a series of puzzles involving the calculation of molarities to discover the formula of a solution that can save a kidnapped scientist. Each solved puzzle leads to a clue that brings them closer to the final solution.

- Instructions:

• Create an engaging story where a scientist is kidnapped and his only hope is a chemical formula based on molarities.

• Divide the class into groups and provide them with the first puzzle, which will lead them to the first part of the formula.

• As groups solve the puzzles, they progress in obtaining the data for the final formula.

• The group that first completes the correct formula wins the 'key' to the scientist's laboratory and rescues him.

• Discuss the solutions found by each group and the importance of each step in solving the mystery.

Feedback

Duration: (15 - 20 minutes)

This stage of the lesson plan aims to consolidate the learning acquired during practical activities, allowing students to articulate and reflect on the applied knowledge. Group discussion helps identify gaps in understanding and share effective strategies, promoting collaborative and deep learning. Additionally, by responding to and listening to peers, students develop communication and critical argumentation skills.

Group Discussion

Start the group discussion with a brief introduction, highlighting the importance of sharing experiences and learnings. Suggest that each group presents a summary of what they accomplished and the solutions found, emphasizing the challenges and strategies used. Encourage students to analyze the differences between the obtained solutions and reflect on what they could have done differently. Ask how they would apply the concept of molarity in real situations outside the classroom.

Key Questions

1. What were the main challenges your group faced while calculating the molarities and how did you overcome them?

2. Was there any situation where the theory studied did not apply correctly? How did you resolve that?

3. How do you envision utilizing the concept of molarity in your lives or future careers?

Conclusion

Duration: (5 - 10 minutes)

The purpose of this stage is to ensure that students have a clear and consolidated understanding of what was learned during the class. By summarizing the content, the teacher helps students organize their memories and link theory to practice, reinforcing learning. Moreover, by highlighting the importance of studying molarity, students are motivated to continue exploring and applying these concepts in other areas of study and in practical life.

Summary

To conclude the class, the teacher should recap the main concepts covered about molarity, reinforcing the fundamental mathematical formula M = n/V and exemplifying the calculation in different contexts. It is important to summarize the activities completed and the results obtained to consolidate learning.

Theory Connection

During the lesson, students were able to experience the practical application of the theory of molarity through playful and challenging activities. Through these practices, the theory was integrated into the students' daily lives, showing the relevance of calculating molarities in real situations and preparing them for future applications.

Closing

In conclusion, it is crucial to highlight the importance of studying molarity for the understanding and manipulation of chemical solutions in everyday life, both in laboratories and in industrial and health contexts. Understanding and being able to calculate molarities is essential to ensure precision and safety in chemical experiments and practical applications.