Overview
Electrochemistry powers our world. It explains how batteries store energy, how metals corrode, and how we can plate gold onto cheap metal.
Core Idea
Redox (Reduction-Oxidation) Reactions: Reactions where electrons are transferred.
- Oxidation: Loss of electrons (OIL).
- Reduction: Gain of electrons (RIG). OIL RIG: Oxidation Is Loss, Reduction Is Gain.
Formal Definition (if applicable)
Galvanic Cell (Voltaic Cell): A device that converts chemical energy into electrical energy (spontaneous). Electrolytic Cell: A device that uses electrical energy to drive a non-spontaneous chemical reaction.
Intuition
Think of a waterfall. Water falling (electrons flowing) releases energy that can turn a turbine (do work). A battery is a chemical waterfall. Recharging a battery is like pumping the water back up to the top.
Examples
- Lithium-ion Batteries: Powering phones and electric cars.
- Corrosion (Rust): Iron oxidizing to form iron oxide.
- Electroplating: Coating jewelry with gold or silver.
Common Misconceptions
- “Anode is always positive.” (In a battery/galvanic cell, the anode is negative. In an electrolytic cell, it’s positive. But oxidation always happens at the anode.)
- “Electrons flow through the salt bridge.” (Ions flow through the salt bridge; electrons flow through the wire.)
Related Concepts
- Standard Reduction Potential ($E^\circ$): A measure of how much a substance wants to gain electrons.
- Nernst Equation: Calculating voltage under non-standard conditions.
- Faraday’s Laws: Relating charge to amount of substance.
Applications
- Energy Storage: Developing better batteries for renewable energy.
- Metallurgy: Extracting aluminum from ore (Hall-Héroult process).
- Neuroscience: Nerve impulses are electrochemical signals.
Criticism / Limitations
Batteries degrade over time due to unwanted side reactions. Storing large amounts of energy efficiently remains a major technological challenge.
Further Reading
- Bard & Faulkner, Electrochemical Methods
- Faraday, Experimental Researches in Electricity