Addition of sodium hydroxide to metal aqua ions
Addition of sodium hydroxide to metal aqua ions
Formula
Al(OH)₃(s) + OH⁻(aq) → [Al(OH)₄]⁻(aq)
Real World
In the Bayer process for extracting aluminium, bauxite ore is dissolved in concentrated NaOH because Al(OH)₃ is amphoteric — iron oxide impurities remain as insoluble solids and are filtered off as red mud.
Exam Focus
State clearly whether the hydroxide dissolves in excess NaOH — Al(OH)₃ does (amphoteric) but Fe(OH)₃ does not; this is a common distinction question.
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