Objectives (5 - 7 minutes)

1. Understanding Colligative Properties: Students should be able to define and explain the concept of colligative properties, identifying how they are influenced by the amount of solute in a solution.

2. Solving Problems Related to Colligative Properties: Students should be able to apply the necessary mathematical formulas and chemical laws to solve problems involving colligative properties.

3. Differentiating Colligative Properties: Students should be able to differentiate colligative properties, identifying how each of them is affected by the amount of solute in a solution.

   Secondary Objectives:

   • Developing Critical Thinking: When solving problems related to colligative properties, students should be encouraged to develop critical thinking, analyzing the data and applying the acquired knowledge effectively.

   • Promoting Teamwork: During problem-solving, students should be encouraged to work in teams, promoting collaboration and effective communication.

Introduction (10 - 15 minutes)

1. Review of Previous Content: The teacher should start the lesson by briefly reviewing the concepts of solutions, solutes, and solvents. It is important for students to clearly understand these concepts as they are essential for understanding colligative properties. Additionally, the teacher can review the types of colligative properties (vapor pressure, boiling point elevation, freezing point depression, and osmotic pressure) that were covered in previous classes. (3 - 5 minutes)

2. Problem Situations: Next, the teacher should present two problem situations that will serve as the basis for theory development and problem-solving.

   a. Problem Situation 1: "Why are roads salted in winter to prevent ice formation?"

   b. Problem Situation 2: "Why is the boiling point of a solution (like saltwater) higher than the boiling point of the pure solvent (pure water)?" (3 - 5 minutes)

3. Contextualization: The teacher should then contextualize the importance of studying colligative properties, explaining how these concepts are applied in everyday situations and in areas such as the food, pharmaceutical, and chemical industries. For example, colligative properties are fundamental for ice cream production, drug formulation, and chemical product manufacturing. (2 - 3 minutes)

4. Topic Introduction: To spark students' interest in the topic, the teacher can share some curious or interesting applications of colligative properties. For example:

   a. Curiosity 1: "Did you know that cryoscopy is used to determine the amount of salt in a sample of seawater? This is because adding salt to water decreases the freezing point of water."

   b. Curiosity 2: "Did you know that geckos can walk on the ceiling due to vapor pressure? The tiny fibers on their feet increase the contact area, reducing the vapor pressure and allowing them to adhere to the surface." (2 - 3 minutes)

Development (20 - 25 minutes)

1. Theory of Colligative Properties (5 - 7 minutes): The teacher should start explaining the theoretical content, addressing each of the colligative properties (vapor pressure, boiling point elevation, freezing point depression, and osmotic pressure).

   a. Vapor Pressure: The teacher should explain that the vapor pressure of a solution is the pressure exerted by the vapors of the solvent and solute on the surface of the solution. It should be emphasized that vapor pressure is inversely proportional to the solute concentration in the solution.

   b. Boiling Point Elevation: The teacher should explain that boiling point elevation is the increase in the boiling point of a solvent when a non-volatile solute is dissolved in it. It should be highlighted that the increase is proportional to the solute concentration.

   c. Freezing Point Depression: The teacher should explain that freezing point depression is the decrease in the freezing point of a solvent when a non-volatile solute is dissolved in it. It should be emphasized that the decrease is proportional to the solute concentration.

   d. Osmotic Pressure: The teacher should explain that osmotic pressure is the decrease in the maximum vapor pressure of a solvent when a non-volatile solute is dissolved in it. It should be emphasized that the decrease is proportional to the solute concentration.

2. Problem Situations Resolution (10 - 12 minutes): The teacher should revisit the problem situations presented in the Introduction and explain how colligative properties apply to them.

   a. Problem Situation 1: The teacher should explain that adding salt to the road decreases the vapor pressure of water, causing it to evaporate at a lower temperature, thus preventing ice formation.

   b. Problem Situation 2: The teacher should explain that adding salt to water increases the boiling point of water, causing it to boil at a higher temperature.

3. Practical Examples (5 - 6 minutes): The teacher should present some practical examples of problems involving colligative properties and guide students in solving them.

   a. Example 1: "What will be the boiling point of a solution made by dissolving 20 grams of sugar (C12H22O11) in 250 ml of water?"

   b. Example 2: "What will be the freezing point of a solution made by dissolving 50 grams of sodium chloride (NaCl) in 500 ml of water?"

   c. Example 3: "What will be the maximum vapor pressure of a solution made by dissolving 30 grams of glucose (C6H12O6) in 200 ml of water?"

The teacher should guide students in solving these examples, explaining step by step how to apply the formulas and chemical laws to arrive at the correct answers.

4. Group Discussion (3 - 5 minutes): To promote interaction and critical thinking, the teacher should divide the class into groups and ask them to discuss the solutions to the examples, explaining the reasoning used and the difficulties encountered. Each group should then present their conclusions to the class.

This is an important moment for the teacher to clarify any doubts that may arise and for students to reinforce what they have learned by discussing the content among themselves.

Note: Throughout the lesson development, the teacher should always reinforce the importance of understanding and correctly applying colligative properties, as they are fundamental for problem-solving in this context. Additionally, the teacher should encourage students to ask questions and actively participate in the lesson, thus promoting a collaborative and engaged learning environment.

Return (8 - 10 minutes)

1. Connection to Practice (3 - 4 minutes): The teacher should revisit the problem situations presented in the Introduction and ask students to reflect on how the theory of colligative properties was applied to solve them. Students should be encouraged to make connections between theory and practice, realizing how the acquired knowledge can be applied to solve everyday problems. For example:

   • Problem Situation 1: "How does adding salt to the road reduce ice formation?" Students should be encouraged to explain that adding salt to the road decreases the vapor pressure of water, causing it to evaporate at a lower temperature, thus preventing ice formation.

   • Problem Situation 2: "Why is the boiling point of a solution (like saltwater) higher than the boiling point of the pure solvent (pure water)?" Students should be encouraged to explain that adding salt to water increases the boiling point of water, causing it to boil at a higher temperature.

2. Concepts Review (2 - 3 minutes): The teacher should ask students what were the most important concepts they learned during the lesson. The teacher should then review these concepts, clarifying any doubts that may have arisen. Additionally, the teacher should emphasize the importance of understanding and correctly applying colligative properties, as they are fundamental for problem-solving in this context.

3. Individual Reflection (2 - 3 minutes): The teacher should propose that students reflect for a minute on the following questions:

   1. "What was the most important concept you learned today?"
   2. "What questions have not been answered yet?"

   After a minute of reflection, the teacher should ask some students to share their answers with the class. This will allow the teacher to assess students' understanding of the topic and identify any gaps in understanding that may need additional clarification.

4. Feedback and Closure (1 - 2 minutes): To conclude the lesson, the teacher should thank the students for their participation, provide brief feedback on the lesson, and inform about what will be covered in the next lesson. The teacher should also encourage students to continue studying the topic and to clarify any doubts that may have arisen.

Conclusion (5 - 7 minutes)

1. Content Summary (2 - 3 minutes): The teacher should briefly review the main points covered during the lesson, reinforcing the concepts of colligative properties and how they are applied to solve problems. The teacher should highlight the differences between colligative properties (vapor pressure, boiling point elevation, freezing point depression, and osmotic pressure) and how each of them is affected by the amount of solute in a solution.

2. Connection between Theory, Practice, and Applications (1 - 2 minutes): The teacher should reiterate the importance of connecting the theory learned with practice and real-world applications. The teacher should mention again the problem situations presented in the Introduction and how the concepts of colligative properties were applied to solve them. Additionally, the teacher should remind students how these concepts are applied in everyday situations and in areas such as the food, pharmaceutical, and chemical industries.

3. Extra Materials (1 - 2 minutes): The teacher should suggest some extra materials for students who wish to deepen their knowledge of colligative properties. These materials may include chemistry books, educational videos online, chemistry websites, among others. The teacher should encourage students to explore these materials at their own pace and to clarify any doubts that may arise.

4. Subject Importance (1 minute): Finally, the teacher should emphasize the importance of the subject covered for students' daily lives. It should be emphasized that understanding colligative properties is crucial for the comprehension of various chemical processes, as well as having practical applications that affect daily life. For example, the teacher can mention how adding salt to the road to prevent ice formation, or understanding the boiling point of water in food preparation, are situations where knowledge of colligative properties is applied.

This Conclusion stage is essential to consolidate students' learning, reinforce key concepts, and motivate them to continue studying and exploring the topic. Additionally, by highlighting the relevance of the subject to daily life, the teacher helps to spark students' interest and motivation in chemistry, showing how it is present in a practical and meaningful way in their lives.