Electrochemistry

Electrochemistry

• Electrochemistry is the study of the relationship between electricity and chemical reactions.

Electrolytic Cells

• In an electrolytic cell, an electric current is passed through an electrolyte to cause a chemical change.
• The electrolyte is a substance that contains free ions, allowing it to conduct electricity.
• The chemical change happens because the applied electric current causes ions to gain or lose electrons, a process called redox reaction.

Redox Reactions

• Redox is a type of reaction that involves both reduction (gain of electrons) and oxidation (loss of electrons).
• The species that loses electrons is said to be oxidised while the one that gains electrons is said to be reduced.
• These reactions occur at the electrodes of the electrolytic cell: oxidation happens at the anode (negative electrode) while reduction occurs at the cathode (positive electrode).

Electrochemical Cells (Batteries)

• Electrochemical cells, or batteries, generate an electric current from a chemical reaction.
• The chemical reaction provides the energy needed to move electrons from the anode to the cathode, creating an electric current.
• When connected in a circuit, this movement of electrons can be used to power electrical devices.
• The overall energy change in an electrochemical cell is given by the cell’s voltage or electromotive force (EMF).

Electrode Potentials

• Electrode potentials measure the ability of a half-cell to force electrons onto or take electrons from the other half-cell in the cell.
• They are measured under standard conditions (1M solution, 100kPa pressure, and 298K temperature) and are expressed in volts (V).
• The electrode potential of a cell is calculated by subtracting the potential of the anode from the potential of the cathode.

Faraday’s Laws of Electrolysis

• Faraday’s first law states that the mass of a substance deposited at an electrode during electrolysis is directly proportional to the amount of electricity passed.
• Faraday’s second law states that the mass of a substance deposited at an electrode during electrolysis is directly proportional to the relative atomic mass (Ar) of the substance and inversely proportional to the number of electrons involved in the redox reaction.
• These laws can be used to calculate the amount of substance gained or lost during an electrolysis experiment.

Applications of Electrochemistry

• Electrochemistry has many real-world applications, including electroplating, manufacturing batteries, and electrolysis reactions in industries.
• Electroplating is the process of using electrolysis to coat a metal object with a thin layer of a different metal.
• Batteries use electrochemical reactions to store and provide energy for electrical devices.
• In industry, electrolysis is used to produce key substances, such as chlorine from saltwater or aluminium from bauxite.