Electrochemical Cells and Standard Electrode Potentials

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Subject: Chemistry

Semester: 2

Period: 4

Week: 20

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School Name:
Teacher’s Name:
Subject: Chemistry
Grade Level: Grade 11
Week & Period: Week 20, Period IV
Date:

Topic: Electrochemical Cells and Standard Electrode Potentials

Subtopics:

• Electrochemical cells
• Standard electrode potential (E°)
• Cell diagrams
• Electromotive force (emf) of cells

 

Learning Objectives

By the end of the lesson, learners should be able to:

1. Define and explain the construction of electrochemical cells
2. Interpret and draw standard cell diagrams
3. Calculate the electromotive force (emf) of a cell using standard electrode potentials
4. Explain the movement of electrons and direction of current in a cell

 

Previous Knowledge

Learners understand redox reactions and can balance redox equations. They also know oxidation and reduction occur together.

 

Instructional Materials

• Electrochemical cell diagrams
• Standard electrode potential chart
• Sample Daniell cell model or virtual simulation
• Multimeter or voltmeter for demonstration

 

Anticipation (Warm-Up) – 5 minutes

Ask learners: “How do batteries produce electricity?” Use a lemon cell or Daniell cell demonstration to spark interest. Highlight that redox reactions power these devices.

 

Building Knowledge (Main Lesson) – 25 minutes

1. What is an Electrochemical Cell?
   An electrochemical (galvanic/voltaic) cell converts chemical energy to electrical energy using spontaneous redox reactions. It consists of two half-cells connected by a salt bridge.
2. Cell Setup

• Anode: oxidation occurs (negative electrode)
• Cathode: reduction occurs (positive electrode)
• Salt bridge: maintains charge balance by allowing ion flow
• Electrons flow from anode to cathode

3. Cell Diagram Representation

• Format: Anode | Anode solution || Cathode solution | Cathode
• Example: Zn(s) | Zn²⁺(aq) || Cu²⁺(aq) | Cu(s)

4. Standard Electrode Potential (E°)

• Measured under standard conditions: 25°C, 1 atm, 1 M solutions
• Electrode potential is a measure of the tendency of a half-cell to gain or lose electrons
• Standard hydrogen electrode (SHE) is the reference (E° = 0 V)

5. Calculating Cell emf (E°cell)
   E°cell = E°cathode – E°anode
   A positive E°cell indicates a spontaneous reaction.
6. Application to Daniell Cell
   Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)
   E°cell = 0.34 V – (–0.76 V) = 1.10 V

 

Learners’ Activities

• Label parts of a galvanic cell diagram
• Use standard electrode potential values to calculate emf
• Draw and interpret at least two cell diagrams
• Use simulations or diagrams to track electron flow and ion movement

 

Consolidation (Review and Assessment) – 10 minutes

• Oral Q&A: “Which electrode is oxidized?” “What does a positive emf mean?”
• Quick calculation: Find E°cell for a given redox pair
• Peer review of drawn cell diagrams

 

Homework / Assignment

1. Write standard cell diagrams for the following combinations:
   Mg and Ag⁺
   b. Fe and Cu²⁺
2. Use the standard electrode potentials to calculate the emf for each
3. Research how the salt bridge affects the function of an electrochemical cell

 

Notes – Detailed and Explained

Electrochemical Cells work through redox reactions. The anode releases electrons (oxidation) while the cathode gains electrons (reduction). These electrons travel through an external wire, generating electricity.

Salt Bridge is a key feature—it allows ions to flow and maintain neutrality in both half-cells.

Standard Electrode Potential (E°) is a quantitative measure of how easily a species gains or loses electrons. These values are used to calculate the cell emf, which tells us whether the reaction can occur spontaneously.

A positive emf indicates the cell can produce electrical energy. A negative emf would suggest a non-spontaneous reaction (electrolysis would be required).

Cell Diagrams are a shorthand way to show the components of a cell and the direction of electron flow. Mastery of these diagrams is essential for understanding battery chemistry and electrochemical reactions in practical fields.

 

Expanded Notes / Instructions

• Use physical models or animations to show ion/electron flow
• Highlight differences between electrochemical and electrolytic cells
• Emphasize the real-world connection to batteries and corrosion

 

Inclusive / Differentiation

• Guided handouts with electrode potential charts
• Pair up learners for peer-supported emf calculations
• Advanced learners can explore voltaic series and predict redox reactions

 

Teacher’s Reflection (Post-Lesson Questions)

• Were learners confident in using E° values to predict emf?
• Did they grasp the direction of electron flow in the diagram?
• Should I revisit the cell diagram syntax or electrode rules?