Chemical Effects of Electric Current 8 Science — Revision Notes
Electric current flowing through certain solutions can cause chemical reactions, leading to decomposition, displacement, and plating. These effects have pr
TL;DR: Electric current flowing through certain solutions can cause chemical reactions, leading to decomposition, displacement, and plating. These effects ha…
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Electric current flowing through certain solutions can cause chemical reactions, leading to decomposition, displacement, and plating. These effects have pr
Electrolysis Concept
- Electrolysis is the process of chemical decomposition using electric current
- Electric current flows through a solution containing ions
- Positive ions move to cathode, negative ions move to anode
- Chemical changes occur at the electrodes
- Electrolysis requires external source of electrical energy
Electrolysis of Water
- Water can be decomposed into hydrogen and oxygen using electric current
- Hydrogen gas forms at cathode, oxygen gas forms at anode
- Oxygen is collected twice the volume of hydrogen
- Sulphuric acid is added to increase conductivity of water
- This demonstrates chemical change due to electric current
Electroplating Process
- Electroplating is coating a metal object with another metal using electrolysis
- Object to be plated is cathode, coating metal is anode
- Coating metal dissolves from anode and deposits on cathode
- Electrolyte is a salt solution of the coating metal
- Applications include chrome plating, silver plating, and gold plating of jewelry
Electrometallurgy
- Extraction of metals from ores using electrolysis
- Aluminum is extracted from bauxite using electrolysis
- Copper is refined using electrolysis for high purity
- More reactive metals are extracted using electrolysis rather than reduction
- Industrial scale electrolysis requires large amounts of electrical energy
Conduction and Conductors
- Ionic compounds conduct electricity when dissolved or molten
- Aqueous solutions of acids, bases, and salts are good conductors
- Pure water is a poor conductor; impurities increase conductivity
- Metallic conductors allow electron flow; ionic solutions allow ion flow
- Electrode material affects the type of chemical reaction in electrolysis
Key Terms
- Electrolysis: Chemical decomposition of a substance using electric current
- Electroplating: Process of coating an object with a thin layer of another metal using electrolysis
- Electrode: Conductor through which electric current enters or leaves a solution
- Electrolyte: Substance that conducts electricity when dissolved or molten
Frequently Asked Questions
Why is sulphuric acid added to water before electrolysis?
Pure water is a poor conductor. Adding sulphuric acid increases the concentration of ions, improving electrical conductivity.
What is the purpose of electroplating?
Electroplating protects metals from corrosion, provides aesthetic appeal, and improves wear resistance of surfaces.
More 8 Science Revision Notes
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- Cell: Structure and Functions
- Reproduction in Animals
- Force and Pressure
- Sound
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