Lesson Plan | Active Learning | Solutions: Solubility

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 - 7 minutes)

The Objectives stage is essential to guide both the teacher and the students on what will be the focus of learning during the lesson. In this stage, the objectives are clearly outlined so that all involved understand the learning goals. By establishing these objectives, students are prepared for the upcoming practical activities, aware of what is expected of them to learn and apply.

Main Objectives:

1. Empower students to identify and verify the solubility limit of a substance in a solvent.

2. Develop the ability to understand and explain how solubility varies with temperature.

3. Enable students to perform calculations to determine the maximum amount of solute that can be dissolved in a specific amount of solvent under different temperature conditions.

Side Objectives:

1. Encourage collaboration among students during practical activities to foster mutual learning.

Introduction

Duration: (15 - 20 minutes)

The Introduction serves to engage students and review key concepts of solubility, laying the groundwork for practical activities. The problem situations encourage students to think critically and apply prior knowledge in a practical and contextualized manner. Contextualization, in turn, shows the relevance of the topic in everyday life, increasing interest and awareness of the importance of studying solubility.

Problem-Based Situations

1. Imagine you have to prepare a saturated salt solution in water for a chemical experiment. How would you determine the maximum amount of salt that can be dissolved in 100 ml of water at 20°C?

2. You are in a kitchen and need to make very sweet lemonade. When mixing sugar and water, you notice that after adding 200g of sugar, the liquid is still clear. How could you determine if it is possible to dissolve more sugar in the water?

Contextualization

Solubility is not just an abstract concept in chemistry; it has practical applications in various fields, from the pharmaceutical industry to cooking. For example, understanding how temperature affects solubility is crucial for the production of medications and the creation of new formulations. In addition, the ability to control solubility is essential in preparing beverages, such as teas and coffees, where the amount of solute dissolved can drastically alter the flavor and effectiveness of the final product.

Development

Duration: (75 - 85 minutes)

The Development stage is designed for students to practically and contextually apply solubility concepts, focusing on determining solubility limits and how they vary with temperature. Through the activities, students will visualize and manipulate dissolution phenomena, promoting more meaningful and lasting learning. Each activity is structured to encourage investigation, teamwork, and communication skills, essential in scientific development.

Activity Suggestions

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

Activity 1 - The Crystal Race

> Duration: (60 - 70 minutes)

- Objective: Determine the solubility of different substances in water and how this solubility varies with temperature.

- Description: In this activity, students will be challenged to determine the solubility of different substances in water at different temperatures. They should prepare saturated solutions of salt, sugar, and baking soda in water at different temperatures and visually assess the saturation. The objective is to determine which substance is more soluble in water and how temperature affects solubility.

- Instructions:

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

• Each group receives 3 beakers containing water and thermometers, and 3 solid samples of salt, sugar, and baking soda.

• Students should weigh each solid sample and note the initial weight.

• Next, they should add the first sample to a beaker and stir until it stops dissolving, recording the temperature. This will be done for each solid at different temperatures.

• After dissolution, students should filter the solution to remove any undissolved solid and weigh the beaker again to calculate the mass of dissolved solid.

• Use the data to create a solubility graph against temperature for each substance.

Activity 2 - The Sweet Lemonade Mystery

> Duration: (60 - 70 minutes)

- Objective: Determine the maximum solubility of sugar in water at different temperatures using heating and cooling methods.

- Description: Students are challenged to determine whether it is possible to dissolve more sugar in already saturated water. They should use heating and cooling methods to test the solubility of sugar in water at different temperatures. The challenge is to try to dissolve the maximum amount of sugar possible and determine the maximum solubility at each tested temperature.

- Instructions:

• Students form groups of up to 5 people and receive 1 liter of water and 500g of sugar.

• Each group should create a saturated sugar solution in water at room temperature, stirring until no more dissolves.

• Once the solution is saturated, they must split the solution into equal parts and test the solubility of sugar at different temperatures, using water baths and ice.

• Students should record the amount of sugar added and the temperature for each test. They should also visually observe whether the sugar completely dissolves or if there are crystals at the bottom.

• With the collected data, they must calculate the maximum solubility of sugar in water at each temperature.

Activity 3 - The Party of Floaters and Sinks

> Duration: (60 - 70 minutes)

- Objective: Relate the solubility of substances in water to the density of the solutions and the behavior of submerged objects.

- Description: In this playful activity, students will explore the solubility of different substances in water in an unconventional way. They will prepare saturated solutions of salt, sugar, and baking soda, and test whether various objects (like coins, sticks, or small toys) float, sink, or remain suspended in the solution based on the solution's density.

- Instructions:

• Students are divided into groups, and each group receives 3 saturated solutions of different substances in water.

• They also receive a variety of objects of different densities.

• Students should test each object in the different solutions and record whether the object floats, sinks, or remains suspended.

• After testing all objects in the solutions, they should attempt to explain the results based on the solubility of the substances and the density of the solutions.

Feedback

Duration: (15 - 20 minutes)

The purpose of this feedback stage is to consolidate learning, allowing students to articulate what they have learned and reflect on the investigative process. Group discussion helps reinforce solubility concepts and their relationship with temperature, as well as promote communication and collaboration skills. This time also serves for the teacher to assess students' understanding and clarify any remaining doubts.

Group Discussion

To start the group discussion, the teacher should ask each group to share their findings and results from the activities. It is important for students to describe the procedures used, observations made, and conclusions reached. The teacher can begin with a brief recap of the activities performed, highlighting the importance of understanding solubility and how it relates to real-world contexts, such as food preparation or industrial processes.

Key Questions

1. What were the main challenges you faced when determining the solubility of substances at different temperatures?

2. How did temperature affect the solubility of the tested substances? Were there any surprises in the results?

3. What is the importance of understanding solubility in practical applications, such as in industry or daily life?

Conclusion

Duration: (5 - 10 minutes)

The Conclusion serves to consolidate learning, allowing students to articulate what they have learned and understand the applicability of the concepts studied. Additionally, it helps reinforce the connection between theory and practice, ensuring that students not only absorb knowledge but also recognize its relevance and utility. This stage is essential to ensure that students leave the class with a clear and deep understanding of the topic, ready to apply the knowledge in future situations.

Summary

In this final section, the teacher should recap and summarize the main points covered during the class, emphasizing the determination of the solubility of different substances in water and how this solubility varies with temperature. It is important to revisit the techniques for preparing saturated solutions and the methods used to calculate maximum solubility.

Theory Connection

Today's lesson connected theory and practice in an integrated way, allowing students not only to understand solubility concepts at a molecular level but also to apply them in practical and experimental situations. The proposed activities served as a bridge to apply theoretical knowledge in real-world and everyday contexts, such as in the food and pharmaceutical industries.

Closing

Finally, it is crucial to highlight the importance of solubility in daily life, such as in food preparation or industrial production, where precise control of solubility is essential to ensure the quality and efficacy of products. The concepts explored today are fundamental for understanding many chemical processes and for solving practical problems that arise in various fields.