Electrochemistry 12 Chemistry — Revision Notes
Electrochemistry studies reactions involving electron transfer. Understanding oxidation-reduction reactions, galvanic cells, and electrolysis is fundamenta
TL;DR: Electrochemistry studies reactions involving electron transfer. Understanding oxidation-reduction reactions, galvanic cells, and electrolysis is funda…
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Electrochemistry studies reactions involving electron transfer. Understanding oxidation-reduction reactions, galvanic cells, and electrolysis is fundamenta
Oxidation and Reduction
- Oxidation is loss of electrons; reduction is gain of electrons
- Oxidizing agent accepts electrons; reducing agent donates electrons
- Oxidation number helps track electron transfer
- Rules for assigning oxidation numbers ensure consistency
- Redox reactions always involve simultaneous oxidation and reduction
Galvanic Cells
- Galvanic cell converts chemical energy to electrical energy
- Anode is where oxidation occurs; cathode where reduction occurs
- Electrons flow from anode to cathode through external circuit
- Salt bridge maintains electrical neutrality
- Cell potential equals cathode potential minus anode potential
Nernst Equation
- Nernst equation relates cell potential to ion concentrations
- E equals E0 minus (0.059/n) times log(Q) at 25 degrees Celsius
- Q is reaction quotient; affects voltage based on concentrations
- Standard cell potential E0 is measured under standard conditions
- At equilibrium, Q equals K and cell potential equals zero
Electroplating and Electrolysis
- Electrolysis uses electrical energy to drive non-spontaneous reactions
- Electroplating deposits metal coating on object
- Faraday's laws relate charge to substance deposited
- Industrial applications include refining metals and extracting elements
- Electrolysis of water produces hydrogen and oxygen
Applications of Electrochemistry
- Batteries and fuel cells provide electrical power
- Corrosion involves spontaneous oxidation of metals
- Cathodic protection prevents corrosion using sacrificial anodes
- Electroplating improves durability and appearance of metals
- Analytical techniques like potentiometry use electrochemistry
Key Terms
- Oxidation: Loss of electrons by a substance
- Reduction: Gain of electrons by a substance
- Galvanic Cell: Device that converts chemical energy to electrical energy
- Electrode Potential: Voltage difference at an electrode compared to standard hydrogen electrode
Frequently Asked Questions
Why do metals corrode when exposed to oxygen and water?
Metals are oxidized by oxygen and water, losing electrons. This spontaneous redox reaction forms metal oxides and hydroxides, causing corrosion and deterioration.
What determines whether a redox reaction is spontaneous?
A reaction is spontaneous if the standard cell potential E0 is positive. Positive E0 means the reduction at cathode is thermodynamically favorable.
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