Types of Electrodes in Electrochemistry

Understanding the components that enable redox reactions

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What is an Electrode?

An electrode is a solid conductor (usually a metal or graphite) that facilitates the transfer of electrons to and from the electrolyte. In an electrochemical cell, oxidation occurs at the anode and reduction at the cathode.

Types of Electrodes

1. Inert Electrodes

These do not react with the electrolyte or the ions involved. Examples: Platinum, Graphite.

2. Active Electrodes

These participate in the redox reaction. Common examples: Zinc, Copper.

3. Metal-Metal Ion Electrodes

Consist of a metal in contact with its ion solution. Example: Zn/Zn²⁺.

4. Gas Electrodes

Include a gas, usually with a platinum conductor. Example: Hydrogen electrode.

5. Metal-Insoluble Salt Electrodes

Made from a metal and its slightly soluble salt. Example: Ag/AgCl.

6. Redox Electrodes

Used when both oxidized and reduced species are in solution. Inert electrode (like Pt) is used.

Summary Table

Type	Material	Function / Use
Inert	Pt, Graphite	Conduction only, no reaction
Active	Zn, Cu, Ag	Participates in redox reaction
Metal-Ion	Metal rod + ion solution	Standard redox half-cells
Gas	H₂, O₂ with Pt	Redox involving gases
Metal-Salt	Ag/AgCl	Reference electrode
Redox	Pt with ions in soln	Transfers electrons for redox pair

Electrodes are the foundation of every electrochemical reaction — from batteries to biosensors.

Quick Quiz: True or False?

• ✅ Platinum is an example of an inert electrode. — True
• ❌ All electrodes participate in redox reactions. — False
• ✅ Ag/AgCl is used as a reference electrode. — True

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Related Posts:

• Difference Between Galvanic and Electrolytic Cells
• Types of Electrochemical Cells
• Standard Hydrogen Electrode – Working & Construction

Quiz: Types of Electrodes

1. Which of the following is an example of an inert electrode?
   A. Zinc
   B. Copper
   C. Platinum
   D. Silver
   Correct Answer: C. Platinum
   Explanation: Platinum does not participate in redox reactions and only conducts electrons, making it an inert electrode.
2. What type of electrode is used in the Standard Hydrogen Electrode (SHE)?
   A. Active
   B. Gas
   C. Metal-salt
   D. Redox
   Correct Answer: B. Gas
   Explanation: SHE involves hydrogen gas in contact with a platinum electrode – a classic example of a gas electrode.
3. Which electrode consists of a metal and its slightly soluble salt?
   A. Gas electrode
   B. Redox electrode
   C. Metal-metal ion
   D. Metal-insoluble salt
   Correct Answer: D. Metal-insoluble salt
   Explanation: Example: Ag/AgCl is a metal-insoluble salt electrode, used as a reference.
4. Which of the following electrodes participates in the redox reaction?
   A. Platinum
   B. Graphite
   C. Zinc
   D. All of the above
   Correct Answer: C. Zinc
   Explanation: Zinc is an active electrode, meaning it undergoes oxidation or reduction.
5. In a redox electrode, which material is typically used?
   A. Ag/AgCl
   B. Copper
   C. Platinum
   D. Zinc
   Correct Answer: C. Platinum
   Explanation: Redox electrodes use inert platinum electrodes to facilitate electron transfer without participating in the reaction.