Lesson Plan | Technical Methodology | Concentration Units: Molarity

Objectives

Duration: 10 - 15 minutes

The purpose of this stage is to ensure that students understand the theoretical foundations of molarity, preparing them for subsequent practical activities. This is essential for developing relevant and applicable skills in the job market, such as the ability to perform accurate calculations in laboratory and industrial contexts.

Main Objectives

1. Understand the concept of molarity as the ratio between the number of moles of solute and the volume of the solution.

2. Learn to calculate the molarity of a solution from the provided data.

Side Objectives

1. Identify the importance of molarity in different contexts, such as in the pharmaceutical and food industries.
2. Familiarize themselves with the units of measurement used in the calculation of molarity.

Introduction

Duration: (10 - 15 minutes)

Purpose: The purpose of this stage is to ensure that students understand the theoretical foundations of molarity, preparing them for subsequent practical activities. This is essential for developing relevant and applicable skills in the job market, such as the ability to perform accurate calculations in laboratory and industrial contexts.

Contextualization

Contextualization: Molarity is a fundamental measure in chemistry that allows us to understand the concentration of solutions. Imagine preparing a medicine where the correct amount of active substance is crucial for its effectiveness and safety. Knowing how to calculate molarity ensures that the prepared solutions have the exact concentration needed, avoiding errors that can have serious consequences. Furthermore, molarity is a key concept in various fields of science and industry, ranging from food production to the development of new materials.

Curiosities and Market Connection

Curiosities and Market Connection: Molarity is widely used in the pharmaceutical industry to prepare medications with the correct dosage. In the food industry, it is essential to ensure the quality and safety of products like beverages and preserves, where the concentration of components must be precise. Another interesting application is in the field of biotechnology, where solutions of different concentrations are used in DNA techniques, such as PCR (Polymerase Chain Reaction).

Initial Activity

Initial Activity: Start the class with a thought-provoking question: "How can the concentration of a solution affect the outcome of a scientific experiment or the manufacturing of an industrial product?" Ask students to briefly discuss in groups and share their ideas. Then, show a short video (3-4 minutes) that demonstrates the preparation of a solution in a pharmaceutical laboratory, highlighting the importance of molarity in the process.

Development

Duration: 60 - 65 minutes

The purpose of this stage is to provide students with the practical application of the concept of molarity, as well as to develop skills in calculation and solution preparation. This is essential to ensure that students are prepared to face real challenges in the job market, especially in sectors that require precision, such as the pharmaceutical and food industries.

Covered Topics

1. Definition of Molarity
2. Calculation of Molarity
3. Units of Measurement (mol and liter)
4. Applications of Molarity in Industry

Reflections on the Theme

Guide students to reflect on the importance of precision in molarity calculations. Highlight how errors in these calculations can affect the quality and safety of pharmaceutical and food products, leading to potentially serious consequences.

Mini Challenge

Mini Challenge: Preparing a Solution

Students will be divided into small groups and tasked with preparing a solution with a specific molarity. They must calculate the amount of solute needed and dissolve it in a given volume of solvent.

Instructions

1. Divide the class into groups of 3 to 4 students.
2. Provide each group with the following materials: precision balance, beakers, glass rods, pipettes, solute jars (e.g., sodium chloride), distilled water, and calculators.
3. Distribute a sheet with the desired concentration for the solution (e.g., 1 M of NaCl).
4. Ask students to calculate the mass of NaCl needed to prepare 250 mL of a 1 M solution.
5. After performing the calculations, students should weigh the required amount of NaCl.
6. Guide students to add the NaCl to 250 mL of distilled water, stirring until completely dissolved.
7. Ask students to check the molarity of the prepared solution.

Objective: Develop practical skills in solution preparation and apply molarity concepts in real contexts.

Duration: 25 - 30 minutes

Evaluation Exercises

1. Calculate the molarity of a solution containing 5 moles of solute dissolved in 2 liters of solution.
2. What is the mass of NaOH needed to prepare 500 mL of a 0.5 M solution? (Molar mass of NaOH = 40 g/mol)
3. A solution was prepared by dissolving 10 g of KCl in water until reaching 250 mL. Determine the molarity of the solution. (Molar mass of KCl = 74.5 g/mol)
4. Explain the importance of molarity in the food and pharmaceutical industries.

Conclusion

Duration: (10 - 15 minutes)

Purpose: The purpose of this stage is to consolidate students' learning, ensuring that they understand the practical importance of the concept of molarity. This is essential for them to apply this knowledge in real contexts, both academic and professional, developing critical skills that are valued in the job market.

Discussion

Discussion: Facilitate a discussion among students about how molarity is applied in different contexts, such as in the pharmaceutical and food industries. Encourage them to share their reflections on the challenges they faced in the practical activity and how they resolved the problems encountered. Ask how they see the importance of accurately calculating molarity in real situations and what skills they believe they have developed during the class.

Summary

Summary: Summarize the main points covered in the class: the definition of molarity, the calculation of molarity, the units of measurement used, and the practical applications in the industry. Reinforce the importance of precision in molarity calculations and how this is crucial to ensuring the quality and safety of products in various sectors.

Closing

Closing: Explain how the lesson connected theory with practice by allowing students to apply the concepts of molarity in a realistic solution preparation situation. Highlight the relevance of the topic for the job market and everyday life, emphasizing how the knowledge gained can be useful in various professions. Close the class by reinforcing that the ability to calculate molarity accurately is a valuable and transferable skill for many areas of science and industry.