Lesson plan of Properties of Organic Compounds: Solubility of Organic Compounds

Objectives (5 - 7 minutes)

1. Understand the concept of solubility of organic compounds: The teacher should introduce students to the concept of solubility, explaining that it is the ability of a substance to dissolve in another. In addition, it is important to emphasize that, in the case of organic compounds, solubility is influenced by factors such as the polarity of the molecule and the presence of functional groups.

2. Identify the influence of polarity on solubility: Students should be able to understand how the polarity of a molecule affects its solubility in a solvent. The teacher should explain that polar molecules tend to dissolve in polar solvents, while nonpolar molecules dissolve better in nonpolar solvents.

3. Differentiate the solubility in water and in organic solvents: Students should be able to distinguish the solubility of organic compounds in water and in organic solvents. The teacher should emphasize that, although water is a polar solvent, not all organic compounds are soluble in it due to the presence of nonpolar covalent bonds.

Secondary Objectives

1. Develop critical thinking skills: During the lesson, students should be encouraged to think critically about the subject, making connections between the theory presented and the practical examples.

2. Promote active learning: The teacher should encourage students to actively participate in the lesson, performing practical experiments, discussing the results and asking questions to clarify their doubts.

Introduction (10 - 12 minutes)

1. Review of previous concepts: The teacher should begin the lesson by reviewing important concepts that were covered in previous lessons and that are fundamental to understanding the topic of the current lesson. In this case, it is important to review the concept of organic compounds, polarity of molecules and the nature of covalent bonds. This review can be done through questions directed to students, encouraging active participation and critical thinking.

2. Presentation of problem situations: The teacher may present two problem situations to arouse students' curiosity and introduce the topic of the lesson. For example:

   • Why doesn't oil mix with water?
   • Why do some substances only dissolve in alcohol and not in water, and vice versa?

3. Contextualization of the importance of the subject: The teacher should explain the importance of studying the solubility of organic compounds, highlighting some practical applications, such as the separation of substances in industrial processes, the formulation of medicines and the understanding of biological processes. In addition, it can mention the importance of polarity in solubility for understanding phenomena such as the action of soaps and detergents in cleaning.

4. Introduction of the topic with curiosities: To arouse students' interest, the teacher can share some curiosities related to the topic. For example:

   • Did you know that the solubility of sugar in water increases with temperature? This is because the dissolution of sugar in water is an endothermic process, that is, it absorbs heat.
   • And that carbon dioxide (CO2), which is a gas, can dissolve in water and form carbonic acid (H2CO3), a liquid compound? This is what happens when the CO2 dissolved in the water forms carbonated water (soda drink).

At the end of this stage, students should be engaged and motivated for the learning of the lesson topic, understanding the importance of studying the solubility of organic compounds.

Development (20 - 25 minutes)

1. Substance Dissolution Activity (10 - 12 minutes): The teacher should divide the class into groups of up to 5 students. Each group will receive a tray with water, oil, salt, sugar, and coffee powder. The teacher should instruct students to observe what happens when each of these substances is added to water. Then they should try to make the same observation with oil. Students should record their observations and then the teacher should lead a classroom discussion, asking the groups what they observed and why they think this happened. This activity aims to illustrate the difference between solubility and miscibility, as well as the influence of polarity on solubility.

2. Substance Classification Activity (5 - 7 minutes): Still in groups, students will receive a list of substances (such as glucose, ethanol, acetic acid, methane, water, oil, etc.) and a list of solvents (such as water, ethanol, hexane, etc.). Students must classify the substances in list A according to their solubility in water and in list B according to their solubility in alcohol. They should then discuss their classifications in groups and justify their choices. The teacher should circulate around the room, assisting the groups and clarifying doubts. This activity aims to reinforce the concept of solubility and the influence of polarity on solubility.

3. Solubility Calculation Activity (5 - 6 minutes): Still in groups, students will receive a sheet with several solubility graphs (like the one for KNO3 below) and a table with solubility points of different compounds at different temperatures. Students should analyze the graphs and the table and answer questions such as “Which compound is more soluble in water at 20°C?” or “Does the solubility of compound X increase or decrease with temperature?”. The teacher should circulate around the room, assisting the groups and clarifying doubts. This activity aims to develop the ability to interpret graphical information and tables, in addition to consolidating the concept of solubility and the influence of temperature on solubility.

   KNO3 Solubility Curve:

   

At the end of this stage, students should have consolidated the understanding of the concept of solubility and its relation to the polarity of the substances, besides developing observation, classification and interpretation skills.

Feedback (8 - 10 minutes)

1. Group Discussion (3 - 4 minutes): The teacher should promote a group discussion, where each group will share the conclusions of their activities. Each group will have up to 3 minutes to present their observations and answers. The teacher should encourage the other students to ask questions and make comments, promoting an environment of exchange of ideas and collaborative learning.

2. Verification of Learning (2 - 3 minutes): After the presentations, the teacher should summarize the main points discussed, reinforcing the connection between the theory presented and the practical activities carried out. The teacher should also verify if the learning objectives were achieved, by asking direct questions to the students and requesting that they explain in their own words what they understood about the concept of solubility and its relation to the polarity of the substances.

3. Individual Reflection (2 - 3 minutes): Finally, the teacher should propose that students reflect individually on what they learned in class. To do this, the teacher can ask some questions, such as:

   • What was the most important concept learned today?
   • What questions have not yet been answered?
   • How can you apply what you learned today in everyday situations or in other disciplines? Students should write down their answers in a notebook or evaluation sheet. The teacher should reinforce that reflection is an important step in the learning process, as it helps to consolidate the knowledge acquired and identify possible gaps in understanding.

At the end of this stage, students should have consolidated the knowledge acquired about the concept of solubility and the influence of the polarity of substances, besides having developed critical thinking and reflection skills. The teacher, in turn, should have a clear assessment of the class's progress and of possible learning difficulties that need to be addressed in future lessons.

Conclusion (5 - 7 minutes)

1. Content Summary (2 - 3 minutes): The teacher should begin the conclusion stage by making a brief summary of the main points covered in the lesson. This includes the concept of solubility, the influence of polarity on interactions between molecules and the solubility of organic compounds in water and in organic solvents. The teacher can reinforce these concepts with practical examples that were discussed during the lesson, such as the dissolution of substances in water and oil.

2. Connection between Theory, Practice, and Applications (1 - 2 minutes): Next, the teacher should highlight how the lesson connected theory, practice and applications. For example, the teacher can mention how the substance dissolution activity allowed students to see in practice how polarity affects solubility. In addition, the teacher can highlight how the concept of solubility is applied in everyday situations, such as the preparation of solutions, the formulation of medicines, and the understanding of biological processes.

3. Complementary Materials (1 minute): The teacher should then suggest some complementary materials for students to enhance their knowledge on the subject. This may include chemistry books, educational websites, explanatory videos, and chemical simulation apps. The teacher can also encourage students to review their notes and ask about any doubts they may have.

4. Application of the Subject in Everyday Life (1 minute): Finally, the teacher should emphasize the importance of the studied subject for everyday life. The teacher can mention, for example, how the knowledge about the solubility of substances is useful to understand why some stains are easier to remove with water and others with organic solvents. In addition, the teacher can highlight how the ability to interpret solubility graphs and tables is relevant to several areas, such as the pharmaceutical industry, food chemistry and scientific research.

At the end of this stage, the students should have consolidated the knowledge acquired during the lesson and be motivated to continue learning about the topic. The teacher, in turn, should be assured that the learning objectives were achieved and that the students are prepared for future lessons covering related topics.