Chemical Reactions and equations

Gagan Deep Ahuja delivered an educational video explaining decomposition reactions — chemical reactions where a single compound breaks down into two or more simpler substances using energy in the form of heat, light, or electricity. 1 Three types were covered: thermal decomposition (heat), electrolytic decomposition (electricity), and photolytic decomposition (light). 12

Core Concepts Explained

Decomposition Reaction Definition

• Single compound splits into two or more simpler substances 1

• General form: AB → A + B (one reactant, multiple products) 1

• Opposite of combination reactions 1

• Energy input required to break chemical bonds 1

Types of Decomposition

Thermal Decomposition (Heat-Driven)

• Calcium carbonate (limestone) heated → calcium oxide (lime/quicklime) + carbon dioxide gas 3

• Potassium chlorate (2KClO₃) heated with MnO₂ catalyst → potassium chloride (2KCl) + oxygen gas (3O₂) 2

• Used in various industries 3

Electrolytic Decomposition (Electricity-Driven)

• Water (2H₂O) + electric current → hydrogen gas (2H₂) + oxygen gas (O₂) 24

• Setup uses graphite electrodes, 6-volt battery, and inverted test tubes to collect gases 2

• Water splits into H⁺ ions (move to cathode) and OH⁻ ions (move to anode) 4

• At cathode: 2H⁺ + 2e⁻ → H₂ (hydrogen gas formed) 4

• At anode: 4OH⁻ → O₂ + 2H₂O + 4e⁻ (oxygen gas formed) 4

• Volume ratio: hydrogen collected is 2:1 compared to oxygen 5

Photolytic Decomposition (Light-Driven)

• Silver chloride + sunlight → silver + chlorine 5

• Silver bromide (2AgBr) + light → silver (2Ag) + bromine gas (Br₂) 5

• Pale yellow silver bromide changes to grayish-white silver 5

• Used in black and white photography for film development 6

Characteristics of Decomposition Reactions

• Only one reactant present 6

• Multiple products formed 6

• Requires energy input: heat, light, or electricity 6

Real-Life Applications

• Electrolysis of water 6

• Digestion of food 6

• Extraction of metals 6

• Photographic film development 6