Redox-Reactions-I-By-Prof-Debashis-Ray

Oxidation and Reduction:

• Oxidation: The loss of electrons by a substance.
• Reduction: The gain of electrons by a substance.
• Oxidizing Agent: A substance that causes another substance to undergo oxidation by accepting its electrons.
• Reducing Agent: A substance that causes another substance to undergo reduction by donating its electrons.

Oxidation Number (Oxidation State):

• The assigned number that represents the real or apparent charge of an atom in a compound.
• Rules for Assigning Oxidation Numbers:
  • The oxidation number of an element in its elemental form is 0 (e.g., O₂, H₂).
  • The oxidation number of a monatomic ion is equal to its charge (e.g., Na⁺, Cl⁻).
  • In compounds, hydrogen is typically assigned an oxidation number of +1, while oxygen is typically assigned an oxidation number of -2.
  • The sum of oxidation numbers in a neutral compound is 0.

Balancing Redox Reactions:

• Balancing Half-Reactions: Split the redox reactiocept n into oxidation and reduction half-reactions and balance them separately.
• Conservation of Charge: The total charge on both sides of a balanced redox equation must be equal.
• Conservation of Mass: The number of each type of atom must be the same on both sides of the equation.

Standard Electrode Potentials (E°):

• E° is a measure of the tendency of a half-reaction to occur as a reduction at the standard hydrogen electrode (SHE).
• More positive E° values indicate stronger oxidizing agents, while more negative values indicate stronger reducing agents.

Nernst Equation:

• The Nernst equation relates the electrode potential of a half-cell to the concentrations of reactants and products: E = E° - (0.0592/n) * log(Q) Where:
  • E is the cell potential.
  • E° is the standard cell potential.
  • n is the number of moles of electrons transferred.
  • Q is the reaction quotient.

Faraday’s Laws of Electrolysis:

• First Law: The amount of substance liberated at an electrode during electrolysis is directly proportional to the quantity of electricity passed through the electrolyte.
• Second Law: The masses of different substances liberated by the same quantity of electricity are in the ratio of their chemical equivalent weights.

Standard Hydrogen Electrode (SHE):

• A reference electrode with an assigned potential of 0 volts under standard conditions.
• Used as a reference for measuring the standard electrode potentials of other half-reactions.

Electrochemical Series (Activity Series):

• A list of metals and nonmetals arranged in order of their standard reduction potentials (E°).
• Helps predict the direction of redox reactions and the relative strengths of oxidizing and reducing agents.

Cell Notation:

• Represents the structure of an electrochemical cell, including the electrode materials, phases, and their interactions.

Corrosion:

• The deterioration of metals due to chemical reactions with the environment.
• Often involves oxidation of metal to form metal oxides (e.g., rusting of iron).

Electrolysis:

• The process of using electrical energy to drive a non-spontaneous chemical reaction, such as the decomposition of water into hydrogen and oxygen.

Standard Conditions:

• Standard Temperature and Pressure (STP): 0°C (273.15 K) and 1 atm pressure.
• Standard Concentrations: Typically 1 M for solutions.