Chemistry Class 12 Electrochemistry

ELECTROCHEMISTRY

--- PREREQUISITES --- - Chemical Reactions and Equations - Metals and Non-metals - Periodic Classification of Elements - Acids, Bases and Salts - Thermodynamics (for understanding spontaneity of reactions)

--- MASTER ORGANIZER --- Metal Electrode Half-Cell Table | Half-Cell | Oxidation Reaction | Reduction Reaction | E° | | --- | --- | --- | --- | | Zn | Zn-Zn²? + 2e? | Zn²? + 2e?-Zn | -0.76V | | Cu | Cu²? + 2e?-Cu | Cu-Cu²? + 2e? | +0.34V | | H? | 2H? + 2e?-H? | H?-2H? + 2e? | 0V |

--- FORMULAS & RULES ---
1. Name: Nernst Equation Formula: E = E° - (RT/nF) * ln(Q) Variables: E, E°, R, T, n, F, Q When to use: Calculate the cell potential of a galvanic cell Common trap: Not considering the units of the variables

1. Name: Faraday's Law Formula: m = (Q * M) / (n * F) Variables: m, Q, M, n, F When to use: Calculate the mass of a substance deposited during electrolysis Common trap: Not considering the units of the variables

2. Name: Electrochemical Equivalent Formula: Z = Q / (n * E) Variables: Z, Q, n, E When to use: Calculate the mass deposited per unit of charge Common trap: Not considering the units of the variables

--- DIAGRAMS TO KNOW ---
1. Name: Cell Diagram Key labels: Anode, Cathode, Salt Bridge, Electrolyte What it illustrates: A galvanic cell setup Common exam focus: Understanding the components of a cell

1. Name: Potentiometer Circuit Diagram Key labels: Cell, Potentiometer, Slide Wire What it illustrates: A device to measure the potential difference Common exam focus: Understanding the working of a potentiometer

2. Name: Electrolytic Cell Diagram Key labels: Electrode, Electrolyte, Power Source What it illustrates: An electrolytic cell setup Common exam focus: Understanding the components of an electrolytic cell

--- RAPID REVISION SHEET ---
• An electrochemical cell involves a spontaneous redox reaction
• The standard electrode potential is a measure of the tendency of a half-cell to reduce or oxidize
• The Nernst equation relates the cell potential to the chemical composition of the solution
• Electrolysis involves the transfer of ions through an electrolyte
• The electrochemical equivalent is the mass of a substance deposited per unit of charge
• A galvanic cell produces electricity through a spontaneous redox reaction
• Electroplating involves the deposition of a metal onto another material
• The potentiometer is a device to measure the potential difference between two points
• The corrosion of metals involves an electrochemical reaction

--- COMMON CONFUSIONS SHEET --- Oxidation vs Reduction-Oxidation involves the loss of electrons, while reduction involves the gain of electrons

--- COMMON MISTAKES & TRAPS --- Mistake/Trap-Why it happens-How to avoid - Not considering the units of the variables-Not considering the units of the variables often leads to incorrect calculations-Always check the units of the variables before performing calculations - Not understanding the concept of spontaneity-Not understanding the concept of spontaneity often leads to incorrect analysis of electrochemical reactions-Always analyze the spontaneity of a reaction before drawing conclusions - Not considering the concentration of the solution-Not considering the concentration of the solution often leads to incorrect calculations of the cell potential-Always consider the concentration of the solution when calculating the cell potential

--- EXAM ANSWER BUILDER ---
1. What it tests: Understanding the components of an electrochemical cell Example question: What is the function of the salt bridge in an electrochemical cell? Key tip to answer it well: Always understand the components of a cell before drawing conclusions
2. What it tests: Applying the Nernst equation to calculate the cell potential Example question: Calculate the cell potential of a galvanic cell with a concentration ratio of 0.1 M and 0.01 M. Key tip to answer it well: Always check the units of the variables before performing calculations
3. What it tests: Understanding the concept of electrolysis Example question: What is the difference between electrolysis and electroplating? Key tip to answer it well: Always analyze the spontaneity of a reaction before drawing conclusions