Practice and Revision - Chemical Changes and Reactions

Core concept

A combination reaction forms one product from two or more reactants, like hydrogen and oxygen combining to form water.

How it works

A decomposition reaction breaks down one compound into simpler substances, often needing heat, light, or electricity as energy input.

Why it matters

A displacement reaction occurs when a more reactive element replaces a less reactive one in a compound, like zinc displacing copper from copper sulfate.

Key detail

A double displacement reaction involves an exchange of ions between two compounds, often producing a precipitate (insoluble solid).