Lesson Plan | Lesson Plan Tradisional | Reactions: Redox Equation

Objectives

Duration: (10 - 15 minutes)

This stage aims to ensure students grasp the concept of redox reactions thoroughly. It's crucial for them to understand how the oxidation number (ox) changes for substances involved and to pinpoint both oxidizing and reducing agents. Such understanding will help them follow along and absorb the content presented during the lesson, enabling effective problem-solving and real-life applications of their knowledge.

Objectives Utama:

1. Understand that the redox equation involves the variation of oxidation number (ox) of substances.

2. Identify the substances that undergo oxidation and reduction in a redox reaction.

3. Differentiate oxidizing agents from reducing agents in a redox equation.

Introduction

Duration: (10 - 15 minutes)

The aim of this introductory stage is to provide students with an engaging and informative context for the lesson, showcasing the relevance and prevalence of redox reactions across different facets of life and technology. This will help spark student interest and connect the content to real-world scenarios.

Did you know?

Did you know that redox reactions are key to the functioning of the batteries we rely on in our mobile phones and other gadgets? Moreover, they are also critical in the gold purification process, where both oxidation and reduction help eliminate impurities to yield pure metal. Such examples highlight the significance of redox reactions in our daily lives and modern technology.

Contextualization

Kick off the lesson by discussing how redox reactions play a critical role in various natural and industrial processes. They’re integral to processes like cellular respiration, photosynthesis, metal corrosion, and energy production in batteries. These reactions involve the transfer of electrons, which leads to a change in oxidation number (ox) of the elements. Grasping this concept is vital for understanding numerous chemical reactions and everyday occurrences.

Concepts

Duration: (60 - 70 minutes)

The goal is to reinforce students' comprehension of redox reactions by establishing a strong base in the principles of oxidation and reduction, oxidation number, balancing equations and identifying oxidizing and reducing agents. Through thorough explanations and practical examples, this section aims to equip students to apply these concepts in both academic and everyday settings.

Relevant Topics

1. Definition of Redox Reactions: Explain that oxidation-reduction (redox) reactions involve the transfer of electrons between reactants, resulting in a change in oxidation number (ox) of the elements involved. Clarify that oxidation denotes the loss of electrons, while reduction means gaining electrons.

2. Oxidation Number (Ox): Describe the oxidation number as a useful tool to track electron transfer. Provide illustrations on how to ascertain the ox of various elements in both simple and complex compounds.

3. Balancing Redox Equations: Show how to balance redox equations using first the oxidation-reduction method and then the ion-electron method. Offer detailed, step-by-step examples of the balancing process.

4. Identification of Oxidizing and Reducing Agents: Clarify that the oxidizing agent is the substance that gains electrons and is thereby reduced, while the reducing agent donates electrons and is oxidized. Provide clear examples to help identify agents in various redox reactions.

5. Applications of Redox Reactions: Explore practical applications of redox reactions across industries, biological processes (like cellular respiration and photosynthesis), and daily use (like batteries).

To Reinforce Learning

1. Determine the oxidation number (ox) of chromium in the compound Cr2O7^2-.

2. Balance the following redox equation using the ion-electron method: MnO4^- + Fe^2+ → Mn^2+ + Fe^3+.

3. Identify the oxidizing agent and the reducing agent in the reaction between H2 and O2 to form H2O.

Feedback

Duration: (10 - 15 minutes)

The aim here is to ensure that students have comprehensively understood the concepts and procedures introduced during the lesson. This stage allows for a review of the material, encouraging discourse on answers and involving students actively to clarify doubts, reinforce their learning, and promote critical thinking in various contexts.

Diskusi Concepts

1. Question 1: Determine the oxidation number (ox) of chromium in the compound Cr2O7^2-. 2. To determine the ox of chromium in the dichromate ion (Cr2O7^2-), recall that oxygen generally has an oxidation number of -2. Given there are seven oxygen atoms, the total oxidation contribution from these is -14. The sum of the oxidation numbers must equal the ion's charge, which is -2. Therefore: 3. 2 * (ox of Cr) + 7 * (ox of O) = -2 4. 2 * (ox of Cr) + 7 * (-2) = -2 5. 2 * (ox of Cr) - 14 = -2 6. 2 * (ox of Cr) = 12 7. ox of Cr = 12 / 2 = +6 8. Thus, the oxidation number of chromium in the Cr2O7^2- ion is +6. 9. Question 2: Balance the following redox equation using the ion-electron method: MnO4^- + Fe^2+ → Mn^2+ + Fe^3+. 10. Step 1: Write the half-equations for oxidation and reduction: 11. Oxidation: Fe^2+ → Fe^3+ + e^- 12. Reduction: MnO4^- + 8H^+ + 5e^- → Mn^2+ + 4H2O 13. Step 2: Balance the electrons in the half-equations: 14. Oxidation: Fe^2+ → Fe^3+ + e^- (multiply by 5) 15. 5Fe^2+ → 5Fe^3+ + 5e^- 16. Reduction: MnO4^- + 8H^+ + 5e^- → Mn^2+ + 4H2O 17. Step 3: Combine the half-equations: 18. 5Fe^2+ + MnO4^- + 8H^+ → 5Fe^3+ + Mn^2+ + 4H2O 19. The balanced equation is: 5Fe^2+ + MnO4^- + 8H^+ → 5Fe^3+ + Mn^2+ + 4H2O. 20. Question 3: Identify the oxidizing agent and the reducing agent in the reaction between H2 and O2 to form H2O. 21. In the reaction 2H2 + O2 → 2H2O, hydrogen is oxidized while oxygen is reduced. Therefore: 22. Oxidizing agent: O2 (accepts electrons and is reduced) 23. Reducing agent: H2 (donates electrons and is oxidized)

Engaging Students

1. What steps are crucial for determining the oxidation number (ox) in a compound? 2. Why is balancing redox equations important? What issues could arise if not done correctly? 3. How can you quickly spot the oxidizing agent and the reducing agent in a redox reaction? 4. Can you think of more everyday scenarios where redox reactions happen? Please share them with the class. 5. How are redox reactions utilized in industries? Can you provide specific examples?

Conclusion

Duration: (10 - 15 minutes)

This stage is designed to consolidate and review the concepts covered during the lesson, ensuring that students truly understand the significance and applications of redox reactions. It also aims to bridge theoretical knowledge with practical examples, reinforcing the relevance of the topic to everyday life and across different science and technology fields.

Summary

['Redox reactions entail the transfer of electrons between reactants, leading to a change in oxidation number (ox) of the elements involved.', 'Oxidation signifies the loss of electrons, and reduction means the gain of electrons.', 'The oxidation number (ox) serves as a method to monitor electron transfer.', 'The oxidizing agent is the one that gains electrons and is reduced; conversely, the reducing agent donates electrons and gets oxidized.', 'Balancing redox equations can be achieved using either the oxidation-reduction method or the ion-electron method.', 'Real-world applications of redox reactions include cellular respiration, photosynthesis, metal corrosion, batteries, and metal purification.']

Connection

This lesson linked theory with practical applications by highlighting the critical role of redox reactions in both natural and industrial processes, such as cellular respiration, battery operations, and metal purification, thus enhancing students' comprehension of how these concepts manifest in daily life.

Theme Relevance

Studying redox reactions is essential for a robust understanding of various phenomena we encounter every day as well as industrial applications. For instance, addressing metal corrosion effectively hinges on mastering these reactions, and the batteries we depend on daily rely fundamentally on this understanding. Moreover, vital biological processes like cellular respiration and photosynthesis are centered around redox reactions.