Lesson plan of Stoichiometry: Purity and Yield

Learning Objectives (5-7 minutes)

1. To understand the concept of purity in chemistry and how it is calculated. Students should be able to calculate the purity of a substance based on given data about its composition and impurities.
2. To understand the concept of yield in chemistry and how it is calculated. Students should be able to calculate the yield of a chemical reaction based on given data about the amounts of reactant and product.
3. To apply the concepts of purity and yield to solve problems in stoichiometry. Students should be able to solve problems that involve calculating the amount of pure product obtained from a chemical reaction, given the purity of the reactant and the yield of the reaction.

Secondary Learning Objectives:

• To develop critical thinking and problem-solving skills by applying mathematical and chemical concepts to solve stoichiometry problems.
• To foster collaboration and effective communication among students through group activities and classroom discussions.

Introduction (10-12 minutes)

1. Review of Prior Knowledge: The instructor begins the class by reviewing the concepts of stoichiometry and chemical calculations that were covered in previous lessons. It is important for students to have a solid understanding of these concepts in order to delve deeper into the topic of today's lesson. (3-4 minutes)

2. Problem Situations:

   • The instructor presents a situation in which a chemist needs to calculate the amount of pure product that can be obtained from a chemical reaction, taking into account the purity of the reactant and the yield of the reaction. (2-3 minutes)
   • The instructor then provides a practical example, such as calculating the amount of pure gold that can be obtained from an ore sample, considering the presence of impurities and the efficiency of the extraction process. (2-3 minutes)

3. Contextualization: The instructor explains the significance of the concepts of purity and yield in the chemical industry, emphasizing how these calculations are crucial for producing high-quality chemical substances and for the efficiency of industrial processes. Additionally, the instructor can mention how disregarding these factors can lead to economic and environmental losses. (2-3 minutes)

4. Introduction to the Topic:

   • The instructor introduces the topic of the lesson, explaining that stoichiometry is not limited to calculating amounts of reactants and products, but also involves considering the purity of reactants and the yield of reactions. (1-2 minutes)
   • To capture students' attention, the instructor can share some interesting facts, such as the fact that the chemical industry often has to resort to complex and expensive methods to purify substances, or that discovering new methods to increase the yield of reactions is an active area of research in chemistry. (1-2 minutes)

Development (20-25 minutes)

1. Group Discussion Activity - "The Purity and Yield Challenge" (10-12 minutes)

   • The instructor divides the class into groups of 3-4 students and gives each group a set of cards with different purity and yield problems.
   • Each card contains a problem situation, which could be a chemical reaction with the presence of impurities, the need to calculate the purity of a substance, or the yield of a reaction.
   • Students should discuss and solve the problems in their groups, using the concepts learned in class and the help of the provided support materials.
   • The instructor circulates around the room, assisting groups as needed and observing the progress of the discussions.
   • After a set amount of time, the instructor asks each group to present a solution to one of the problems they discussed. This presentation should include an explanation of the reasoning used to arrive at the solution.

2. Hands-on Activity - "Purity and Yield Calculations in Chemical Reactions" (10-12 minutes)

   • The instructor provides each group with a set of laboratory materials, including reactants, glassware, and a protocol for a chemical reaction.
   • Students should follow the protocol to perform the chemical reaction, taking care to record all quantities used and the results obtained.
   • After completing the reaction, the students should calculate the purity of the reactant and the yield of the reaction, using the experimental data and the concepts learned in class.
   • The instructor circulates around the room, observing the groups' activities and clarifying any doubts.
   • At the end of the activity, each group should present the results of their experiment, including the purity and yield calculations they performed.

3. Application Activity - "Chemical Industry Challenge" (5-10 minutes)

   • The instructor presents the students with a fictitious scenario in which they are chemists working in a pharmaceutical production industry.
   • In this scenario, the students are tasked with calculating the amount of pure product that can be obtained from a chemical reaction, considering the purity of the reactant and the yield of the reaction.
   • Students should work in their groups to solve the challenge, applying the concepts learned in class and the help of the provided support materials.
   • At the end of the activity, each group should present their solution to the challenge, including the calculations they performed and an explanation of the reasoning used.

Closure (8-10 minutes)

1. Class Discussion - "Connections and Reflections" (3-4 minutes)

   • The instructor leads a class discussion, asking each group to share their solutions or conclusions from the activities they completed. Each group will have a maximum of 2 minutes to present.
   • During the presentations, the instructor should highlight the most relevant points and clarify any questions that may arise.
   • After all the presentations, the instructor can facilitate an open discussion, encouraging students to make connections between the activities, the theoretical concepts, and practical applications.
   • The instructor can also ask students to reflect on how the concepts of purity and yield can be applied in other contexts, both inside and outside of chemistry.

2. Review of Learning Objectives (2-3 minutes)

   • The instructor briefly reviews the learning objectives of the lesson, reinforcing the main concepts and skills that were covered.
   • The instructor then asks the students to take a minute to individually reflect on what they learned in the lesson, highlighting the most important concepts and any difficulties they still have.
   • After the minute of reflection, the instructor can invite a few students to share their reflections with the class, facilitating a brief and focused discussion.

3. Feedback and Assessment (2-3 minutes)

   • The instructor asks the students to evaluate the lesson, considering the clarity of the explanations, the relevance of the activities, and the effectiveness of the support materials.
   • The instructor can also ask the students what they enjoyed most about the lesson and what they think could be improved.
   • The students' feedback can be used to refine future lessons and to adjust the pace and content of the course according to the students' needs and interests.
   • Finally, the instructor thanks the students for their active participation and reinforces the importance of continuous study and practice for mastering chemistry concepts.

Conclusion (5-7 minutes)

1. Summary of Key Concepts (2-3 minutes)

   • The instructor reviews the main points discussed during the lesson, reinforcing the concepts of purity and yield in chemistry, and how they are calculated. The instructor can also recap the calculation strategies and formulas used to solve the problems presented.
   • It is important for the instructor to make a connection between the theory and the practical applications, by recalling the examples and activities conducted in class.

2. Supplemental Materials (1-2 minutes)

   • The instructor suggests additional study materials for students who want to further their understanding of purity and yield in chemistry. These materials could include textbooks, chemistry websites, educational videos, and online exercises.
   • For example, the instructor could recommend a video that explains the concepts of purity and yield in a clear and visual way, or a website with a list of stoichiometry exercises for students to practice.

3. Significance of the Topic and Connection to Everyday Life (1-2 minutes)

   • The instructor concludes the lesson by highlighting the importance of the concepts of purity and yield in everyday life and in the industry. For instance, the instructor can mention how these calculations are used in the production of food, medicine, cosmetics, and other chemical products.
   • The instructor can also emphasize the relevance of critical thinking and problem-solving, skills that were developed during the lesson, not only for chemistry but for various areas of life.
   • Finally, the instructor encourages the students to continue exploring the world of chemistry, reminding them that learning is a continuous process and that effort and dedication are essential for success.