Objectives (5 - 7 minutes)

1. Understand the concept of boiling point elevation and its application: Students should understand what boiling point elevation is and how it applies to the study of colligative properties. They should be able to explain boiling point elevation in terms of the increase in the boiling point of a solvent when a non-volatile solute is added.

2. Solve practical problems of boiling point elevation: Students should be able to apply the formula for boiling point elevation to calculate the increase in the boiling point of a solvent when a non-volatile solute is added. They should be able to solve practical problems involving boiling point elevation, such as calculating the molar mass of a solute from the increase in the boiling point.

3. Relate boiling point elevation to everyday situations: Students should be able to identify and describe everyday situations that illustrate boiling point elevation. They should be able to explain how boiling point elevation affects, for example, the cooking time of food or the temperature needed to boil water at high altitudes.

Introduction (10 - 15 minutes)

1. Review of Previous Content: The teacher should briefly review the concepts of colligative properties and, specifically, cryoscopy and tonoscopy. These concepts are fundamental to understanding boiling point elevation, which will be the focus of the lesson. The teacher can ask quick questions to verify if students remember these concepts.

2. Problem Situations: The teacher should present two problem situations involving boiling point elevation. For example:

   • "Why does water take longer to boil at higher altitudes, such as in mountains?"
   • "How does adding salt to water affect the cooking time of food? Why does this happen?"

3. Contextualization: The teacher should explain the importance of boiling point elevation, showing how it is applied in various areas of everyday life. For example:

   • "Boiling point elevation is essential in cooking, as it helps to understand how adding salt to water affects the cooking time of food."
   • "In mountainous regions, boiling point elevation is crucial to know the cooking time of food and the time needed to boil water."

4. Engage Students' Attention: The teacher should present curiosities or interesting facts related to boiling point elevation. For example:

   • "Did you know that boiling point elevation is used in the pharmaceutical industry to determine the purity of a medication, calculating the molar mass of a substance from the increase in boiling point?"
   • "Boiling point elevation is also used in laboratories to determine the molar mass of an unknown solute in a solution. This process is called reverse boiling point elevation and is very useful in scientific research."

This Introduction should prepare students for the Development of the lesson, arousing their curiosity and showing the relevance of the topic.

Development (20 - 25 minutes)

1. Boiling Point Elevation Experiment (10 - 15 minutes)

   • The teacher should divide students into groups of up to five. Each group will receive materials to carry out a practical experiment on boiling point elevation.
   • The necessary materials include: a 250 ml beaker, a heat source (such as a Bunsen burner or stove), thermometer, distilled water, table salt, and a timer.
   • The process of the experiment is as follows:
     1. Each group fills the beaker with 200 ml of distilled water and measures the initial temperature.
     2. Next, the groups add a known amount of table salt to the water (for example, 10 g) and stir until the salt is completely dissolved.
     3. The beaker is placed on the heat source, and the temperature is monitored until the water starts to boil. The time required for this is recorded.
     4. The experiment is repeated similarly, but this time without adding salt to the water. The time required for the water to boil is again recorded.
   • Students should observe that saltwater takes longer to boil than pure water. This is because boiling point elevation increases the boiling point of the solvent (water) when a solute (salt) is added.
   • The teacher should circulate among the groups, guiding and clarifying doubts. In the end, each group should present their results and conclusions to the class.

2. Problem-Solving Activity (10 minutes)

   • After the experiment, students should be asked to solve a practical problem of boiling point elevation. The problem can be similar to what was done in the experiment but with different values.
   • The teacher should provide the formula for calculating the boiling point elevation (ΔTe = Kb * m), where ΔTe is the boiling point elevation, Kb is the molal boiling point elevation constant (which varies according to the solvent), and m is the molality of the solution (which can be calculated from the mass of the solute and the solvent).
   • Students should work in their groups to solve the problem. The teacher should circulate among the groups, providing guidance and clarifying doubts. In the end, each group should present their solution to the class.

3. Group Discussion (5 - 10 minutes)

   • After the problem-solving activity, the teacher should promote a group discussion on boiling point elevation. Students should be encouraged to share their findings, difficulties, and solutions.
   • The teacher should reinforce the main concepts, clarify any remaining doubts, and make connections between boiling point elevation and the everyday situations discussed in the Introduction.
   • This discussion should help solidify students' understanding of boiling point elevation and its application.

Return (8 - 10 minutes)

1. Group Discussion (3 - 4 minutes): The teacher should promote a group discussion where each team shares their solutions and conclusions about the experiment and practical activity carried out. The goal is for students to realize that different approaches can lead to correct solutions and that discussion is an important tool for learning.

2. Connection with Theory (2 - 3 minutes): The teacher should then make the connection between the activities carried out and the theory presented at the beginning of the lesson. The teacher should reinforce that boiling point elevation is a colligative property that refers to the increase in the boiling point of a solvent when a non-volatile solute is added. The teacher should also recall the formula for calculating the boiling point elevation (ΔTe = Kb * m) and how it was applied during the practical activity.

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

   1. What was the most important concept learned today?
   2. What questions have not been answered yet?
   3. How does boiling point elevation relate to the real world?

   Students should write down their answers, which will be used for the next step of the Return.

4. Sharing Reflections (1 - 2 minutes): The teacher should then ask some students to share their answers with the class. This is an opportunity for students to learn from each other and for the teacher to identify any concepts that have not been fully understood by the class.

5. Teacher Feedback (1 minute): The teacher should then provide general feedback on the lesson, highlighting strengths and areas that need to be reinforced. The teacher should also answer any questions that have not been answered yet and reinforce the relevance of boiling point elevation to students' daily lives.

Conclusion (5 - 7 minutes)

1. Review of Main Contents (2 - 3 minutes): The teacher should recap the main points covered in the lesson. This includes the definition of boiling point elevation, the formula for calculating the boiling point elevation (ΔTe = Kb * m), the practical experiment, and problem-solving related to boiling point elevation. This review is important to reinforce students' learning and ensure they have understood the fundamental concepts.

2. Connecting Theory with Practice (1 - 2 minutes): The teacher should highlight how the lesson connected the theory of boiling point elevation with practice. This includes conducting the practical experiment and problem-solving, which allowed students to apply the theoretical concepts of boiling point elevation in a practical and concrete way. The teacher should emphasize the importance of understanding the theory to be able to solve practical problems.

3. Suggestion of Extra Materials (1 minute): The teacher should suggest extra materials for students who wish to deepen their knowledge of boiling point elevation. This may include chemistry books, educational websites, online videos, and learning apps. The teacher should encourage students to explore these materials on their own to complement what was learned in the classroom.

4. Relevance of the Subject (1 - 2 minutes): Finally, the teacher should explain the importance of boiling point elevation for everyday life. This may include examples of how boiling point elevation is used in cooking, the pharmaceutical industry, and scientific research. The teacher should emphasize that chemistry is not just a theoretical subject but something that has practical and relevant applications in the real world.

5. Closure (1 minute): The teacher should end the lesson, reminding students about homework, upcoming classes, and any other relevant information. The teacher should also encourage students to ask any questions they may have and to continue studying the subject on their own.