Precipitation reactions of metal hydroxides
Precipitation reactions of metal hydroxides
Formula
M²⁺(aq) + 2OH⁻(aq) → M(OH)₂(s)
Real World
Water treatment plants add NaOH to remove dissolved iron — the brown Fe(OH)₃ precipitate is filtered out, which is why untreated borehole water often leaves rusty stains on white sinks.
Exam Focus
Learn precipitate colours precisely — Fe²⁺ green, Fe³⁺ brown, Cu²⁺ blue — and note which dissolve in excess ammonia versus excess NaOH.
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