Lesson Plan | Active Learning | Salt Hydrolysis Equilibrium

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: (5-10 minutes)

The objectives stage aims to establish the focus of the lesson and ensure that students clearly understand what is expected of them at the end of the session. By defining clear and specific objectives, students can direct their learning efforts more efficiently, ensuring that classroom activities align with the competencies they need to develop. This stage also serves to motivate students by showing the direct applicability of what they learned at home in solving practical problems in the classroom.

Main Objectives:

1. Empower students to solve practical problems involving the saline hydrolysis of specific salts, determining whether the final solution is acidic or basic.

2. Enable students to calculate the final concentration or pH of solutions resulting from saline hydrolysis processes.

Side Objectives:

1. Develop logical and critical reasoning skills in the analysis of chemical reactions.

Introduction

Duration: (15-20 minutes)

The introduction serves to engage students and connect the concepts studied at home with practical and theoretical applications. The proposed problem situations encourage students to revisit and apply their prior knowledge, preparing them for practical activities in class. Additionally, the contextualization demonstrates the relevance of studying saline hydrolysis in everyday situations and industrial applications, increasing interest and the perception of the importance of the topic.

Problem-Based Situations

1. Imagine you are a chemist working in a laboratory and need to prepare a neutral solution to conduct an experiment. When mixing hydrochloric acid and sodium acetate, what would the chemical reaction be, and how could you determine the proportions needed to obtain a neutral solution?

2. A water treatment company needs to adjust the pH of an industrial effluent before discharging it into the environment. They have an ammonium sulfate solution on hand. How could saline hydrolysis help understand the acidic or basic behavior of this solution and what could be the possible environmental consequences?

Contextualization

Understanding saline hydrolysis is not only crucial in chemistry laboratories but also in various industrial and environmental applications. For example, in wastewater treatment, knowledge of how salts behave in solution helps in preventing environmental pollution. Furthermore, understanding hydrolysis allows for predictions about the behavior of everyday solutions, such as in cooking to adjust the flavor of acidic or basic foods. This ability to apply theoretical knowledge in practical scenarios reinforces the importance of studying saline hydrolysis.

Development

Duration: (75 - 80 minutes)

The development phase is designed to allow students to apply the concepts of saline hydrolysis they studied previously in a practical and interactive way. The proposed activities aim not only to reinforce theoretical knowledge but also to develop teamwork, logical reasoning, and communication skills. By participating in one or more activities, students will be able to solidify their understanding of the chemistry of acid-base equilibria in a fun and educational way.

Activity Suggestions

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

Activity 1 - pH Detectives

> Duration: (60 - 70 minutes)

- Objective: Apply knowledge of saline hydrolysis in practice, developing observation, measurement, and logical reasoning skills.

- Description: In this activity, students will be challenged to solve a 'mystery' involving determining the pH of unknown solutions created from mixing different salts in water. Each group will receive test tubes containing solutions of different salts and must use pH indicators to determine the acidity or basicity of each solution. The goal is to identify which salt, in what proportion and under what conditions, can result in a final solution with the desired pH.

- Instructions:

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

• Distribute chemistry kits equipped with test tubes, Bunsen burners, pH indicators, and a list of different salts.

• Ask each group to choose two salts and prepare solutions of them at different concentrations.

• Students must then measure the pH of each solution and record the results.

• Based on the pH results, students should theorize about the capacity of each salt to produce a final acidic, basic, or neutral solution.

• Each group will present their results and the theory behind their choices of salts and concentrations to achieve the desired pH.

Activity 2 - Reactions on Stage: The Equilibrium Show

> Duration: (60 - 70 minutes)

- Objective: Understand in a playful and interactive way how saline hydrolysis reactions can be influenced by different variables and predict the acid-base behavior of solutions.

- Description: Students will simulate a series of saline hydrolysis reactions on a 'stage' set up in the classroom. Each group will represent a chemical reaction involving the hydrolysis of a specific salt, and the 'audience' (the other groups) must guess whether the final solution will be acidic, basic, or neutral based on the dialogues and actions of the performers (students).

- Instructions:

• Organize the classroom in a layout that allows creating small stages for each group.

• Assign each group a specific salt and its initial conditions of concentration and temperature.

• Groups should prepare a small script that includes dialogues and actions that represent the chemical reactions occurring during saline hydrolysis.

• After each presentation, the other groups should vote on whether the final solution will be acidic, basic, or neutral.

• Final discussion to review the reactions and verify the expected results against the actual results, facilitating the correction of concepts if necessary.

Activity 3 - Chemical Equilibrium Builders

> Duration: (60 - 70 minutes)

- Objective: Develop visual representation skills and explanation of chemical phenomena, while reinforcing the understanding of saline hydrolysis reactions.

- Description: In this activity, groups of students will receive 'ingredients' (different salts, acids, and bases) and must build 'models' of saline hydrolysis reactions on a large whiteboard. Each ingredient will have a specific color to represent the ions involved. Students will then 'assemble' the reactions, predict the outcome, and explain their choices to the class.

- Instructions:

• Provide each group with a color palette that corresponds to the different ions of each reagent.

• Students must use the colors to represent the ions and reactions on the whiteboard.

• Each group chooses a salt and must predict and explain whether the resulting solution will be acidic, basic, or neutral.

• After assembling the model, other groups can 'interact' with the board, asking questions and challenging predictions.

• Conduct a final discussion to compare predictions with the actual behavior of the salts in solution.

Feedback

Duration: (15 - 20 minutes)

This final stage of the lesson plan is essential for consolidating learning, allowing students to reflect on the activities performed and articulate their understanding. The group discussion helps develop communication and argumentation skills, and deepens collective knowledge. Additionally, by answering the key questions, students have the opportunity to apply what they learned in new contexts, strengthening their understanding of saline hydrolysis and its practical importance.

Group Discussion

At the end of the activities, gather all students in a large circle for a group discussion. Begin the discussion by highlighting the importance of sharing what each group learned and the discoveries made during the activities. Encourage each group to briefly present their results and the conclusions reached from their experiences. Review the key concepts discussed, such as the influence of different salts and conditions on saline hydrolysis and how this affects the pH of the resulting solutions. This is a crucial moment for students to compare and contrast their experiences and understandings, enriching collective learning.

Key Questions

1. What were the biggest surprises or challenges your group faced when trying to predict the acid-base behavior of the solutions?

2. How did changes in the concentration of salts influence the pH of the final solutions in your experiments?

3. How did the practical activities help reinforce or change your theoretical understanding of saline hydrolysis?

Conclusion

Duration: (5-10 minutes)

The purpose of the conclusion stage is to ensure that students have a clear and consolidated view of what was learned during the lesson. By summarizing the content, reinforcing the connection between theory and practice, and highlighting the relevance of the topics discussed, students are better able to internalize knowledge and perceive its applicability in the real world. This final reflection helps reinforce learning, preparing students for future applications and studies.

Summary

In the conclusion of the lesson, it is crucial to summarize and recap the main points covered about saline hydrolysis. Students explored how different salts, in aqueous solution, can yield final solutions that are acidic, basic, or neutral, and how these properties are directly related to their ability to react with water and form H+ or OH- ions. Additionally, they discussed and applied the calculation of pH and the concentration of H+ and OH- ions in resulting solutions.

Theory Connection

Today's lesson was structured to coherently link theory to practice. Students not only reviewed the theoretical concepts of saline hydrolysis but also applied them in practical activities that simulated real situations, such as wastewater treatment and the preparation of neutral solutions in the laboratory. This hands-on approach helped solidify theoretical understanding, showing the utility and applicability of chemical knowledge in everyday and professional situations.

Closing

Understanding saline hydrolysis is essential not only for academic success but also for practical application in various fields, such as the chemical industry, water treatment, and product development. The ability to predict and control the acid-base behavior of solutions is a valuable skill that students can carry into their future scientific or technical careers.