Electrochemistry

  • Introduction to Electrochemistry
  • Electrolytes and Electrolysis
  • Conductors and Non-conductors
  • Electrochemical Cells
  • Electrolytic Cells
    • Definition
    • Working Principle
    • Examples
  • Galvanic Cells
    • Definition
    • Working Principle
    • Examples
  • Electrode Potential
    • Definition
    • Standard Hydrogen Electrode (SHE)
    • Measurement of Electrode Potential
  • Oxidation-Reduction Reactions (Redox Reactions)
  • Half-cell Reactions
    • Oxidation Half-cell
    • Reduction Half-cell

Electrochemistry - Questions

  • What is electrochemistry?
  • How are electrolytes and electrolysis related?
  • Explain conductors and non-conductors.
  • What are electrochemical cells?
  • Define an electrolytic cell.
  • Explain the working principle of an electrolytic cell with examples.
  • Define a galvanic cell.
  • Explain the working principle of a galvanic cell with examples.
  • What is electrode potential?
  • Explain the Standard Hydrogen Electrode (SHE).
  • How is the electrode potential measured?
  • Describe the concept of oxidation-reduction reactions (redox reactions).
  • Define half-cell reactions.
  • Explain the oxidation half-cell.
  • Explain the reduction half-cell.
  1. Electrochemical Series
  • Definition
  • Arrangement of metals and non-metals in order of their electrode potentials
  • Example: Li, K, Ba, Ca, Na, Mg, Al, Zn, Fe, Ni, Sn, Pb, H, Cu, Ag, Pt, Au
  1. Nernst Equation
  • Definition
  • Relationship between the concentration of reactants and products and the electrode potential
  • Nernst equation for a reaction: Ecell = E°cell - (RT/nF) * ln(Q)
  • Example: Calculate the electrode potential for the reaction Fe2+(aq) + 2Ag(s) -> 2Ag+(aq) + Fe(s) at 298 K, given [Fe2+] = 0.1 M and [Ag+] = 0.01 M. (Assume E°cell = 0.34 V)
  1. Corrosion
  • Definition
  • Types of corrosion: dry corrosion, wet corrosion, galvanic corrosion, etc.
  • Factors influencing corrosion: presence of moisture, presence of impurities, temperature, pH, etc.
  • Prevention of corrosion: painting, galvanization, sacrificial protection, etc.
  • Example: Rusting of iron in the presence of oxygen and water.
  1. Electroplating
  • Definition
  • Electrochemical process of depositing a metal onto another object
  • Steps involved: cleaning the object, preparing the electrolyte, connecting the object and the anode, passing current, monitoring the process
  • Example: Electroplating of silver onto a copper coin to make it look like a silver coin.
  1. Fuel Cells
  • Definition
  • Electrochemical device that converts the chemical energy of a fuel into electrical energy
  • Types of fuel cells: hydrogen fuel cells, methanol fuel cells, etc.
  • Working principle of a hydrogen fuel cell: hydrogen gas is split into protons and electrons, protons pass through a membrane while electrons flow through an external circuit, protons and electrons combine with oxygen to produce water
  • Advantages and applications of fuel cells
  1. Batteries
  • Definition
  • Electrochemical devices that store and release electrical energy through reversible redox reactions
  • Types of batteries: lead-acid batteries, lithium-ion batteries, etc.
  • Working principle of a lead-acid battery: during charging, lead dioxide and lead react with sulfuric acid to produce lead sulfate and water, during discharging, lead sulfate and water react to produce lead dioxide and lead
  • Advantages and applications of batteries
  1. Faraday’s Laws of Electrolysis
  • Definition
  • Relationship between the amount of substance liberated or deposited during electrolysis and the amount of charge passed through the electrolyte
  • First law: the mass of substance liberated or deposited is directly proportional to the quantity of electricity passed through it
  • Second law: the masses of different substances liberated or deposited by the same quantity of electricity are directly proportional to their stoichiometric coefficients in the balanced chemical equation
  • Example: Electrolysis of water to produce hydrogen and oxygen gas.
  1. Stoichiometry of Electrolysis
  • Definition
  • Calculation of the quantity of substance produced or consumed during electrolysis using Faraday’s laws
  • Example: How many moles of silver are deposited when a current of 2 A is passed through a silver nitrate solution for 180 seconds? (Given: Faraday’s constant = 96500 C/mol)
  1. Galvanic Cells vs. Electrolytic Cells
  • Differences between galvanic cells and electrolytic cells
  • Galvanic cells: spontaneous redox reactions, convert chemical energy into electrical energy, positive cell potential, anode is negative and cathode is positive
  • Electrolytic cells: non-spontaneous redox reactions, convert electrical energy into chemical energy, negative cell potential, anode is positive and cathode is negative
  • Examples and applications of galvanic cells and electrolytic cells
  1. Electrolysis of Water
  • Definition
  • Electrochemical process of decomposing water into hydrogen and oxygen gas
  • Electrolysis of water equation: 2H2O(l) -> 2H2(g) + O2(g)
  • Applications of electrolysis of water: production of hydrogen gas for fuel cells, production of oxygen gas for industrial processes

Electrochemistry - Electrochemical Equilibrium

  • Definition of Electrochemical Equilibrium
  • Electrochemical Equilibrium Constant (K) and its significance
    • Calculation of K
    • Relationship between K and cell potential (ΔEcell)
  • Nernst Equation in terms of Electrochemical Equilibrium
  • Applications of Electrochemical Equilibrium
    • Determining the equilibrium position in redox reactions
    • Predicting the direction of spontaneous redox reactions
  • Example: Calculate the value of the equilibrium constant (K) for the reaction Zn(s) + Cu2+(aq) -> Zn2+(aq) + Cu(s), given that the standard electrode potentials are E°Zn2+/Zn = -0.76 V and E°Cu2+/Cu = 0.34 V.

Corrosion and Prevention

  • Types of corrosion: dry corrosion, wet corrosion, galvanic corrosion, etc.
  • Factors influencing corrosion: presence of moisture, presence of impurities, temperature, pH, etc.
  • Preventing corrosion using coatings
    • Painting
    • Galvanization
  • Preventing corrosion using sacrificial protection
    • Sacrificial anodes
    • Cathodic protection
  • Example: Explain the process of galvanization used to prevent the corrosion of iron.

Electroplating

  • Definition and significance of electroplating
  • Steps involved in the electroplating process
    • Cleaning the object
    • Preparing the electrolyte
    • Connecting the object and the anode
    • Passing current
    • Monitoring the process
  • Factors affecting the quality of electroplating
    • Concentration of the electrolyte
    • Temperature
    • Current density
    • Plating time
  • Example: Electroplate a copper object with silver using a silver nitrate electrolyte.

Fuel Cells

  • Definition and significance of fuel cells
  • Types of fuel cells: hydrogen fuel cells, methanol fuel cells, etc.
  • Working principle of a hydrogen fuel cell
    • Splitting hydrogen gas into protons and electrons
    • Protons passing through a membrane
    • Electrons flowing through an external circuit
    • Protons and electrons combining with oxygen to produce water
  • Advantages and applications of fuel cells
  • Example: Explain the working principle of a methanol fuel cell.

Batteries

  • Definition and significance of batteries
  • Types of batteries: lead-acid batteries, lithium-ion batteries, etc.
  • Working principle of a lead-acid battery
    • Charging process: lead dioxide and lead react with sulfuric acid to produce lead sulfate and water
    • Discharging process: lead sulfate and water react to produce lead dioxide and lead
  • Advantages and applications of batteries
  • Example: Explain the working principle of a lithium-ion battery.

Faraday’s Laws of Electrolysis

  • Definition and significance of Faraday’s Laws of Electrolysis
  • First Law: relationship between the amount of substance liberated or deposited and the quantity of electricity passed through it
    • Calculation using Faraday’s constant
  • Second Law: relationship between the masses of different substances liberated or deposited
  • Example: Calculate the quantity of aluminum deposited when a current of 1.5 A is passed through an aluminum chloride solution for 2 hours. (Given: Faraday’s constant = 96500 C/mol, atomic mass of aluminum = 26.98 g/mol)

Stoichiometry of Electrolysis

  • Definition and significance of stoichiometry of electrolysis
  • Calculation of the quantity of substance produced or consumed during electrolysis
    • Using Faraday’s constant and Faraday’s laws
  • Example: How many grams of chlorine gas are liberated when a current of 2 A is passed through a sodium chloride solution for 1 hour? (Given: Faraday’s constant = 96500 C/mol, molar mass of chlorine = 35.45 g/mol)

Galvanic Cells vs. Electrolytic Cells

  • Differences between galvanic cells and electrolytic cells
  • Galvanic cells: spontaneous redox reactions, convert chemical energy into electrical energy
  • Electrolytic cells: non-spontaneous redox reactions, convert electrical energy into chemical energy
  • Examples and applications of galvanic and electrolytic cells
  • Example: Differentiate between a galvanic cell and an electrolytic cell using examples.

Electrolysis of Water

  • Definition and significance of electrolysis of water
  • Electrolysis of water equation: 2H2O(l) -> 2H2(g) + O2(g)
  • Electrolysis of water experiment setup and process
  • Applications of electrolysis of water
    • Production of hydrogen gas for fuel cells
    • Production of oxygen gas for industrial processes
  • Example: Perform the electrolysis of water experiment and observe the products formed.