Interaction | Reaction | Process     Data Page

When excess hydroxide is added to a colourless solution of hexaaquaaluminium ion, first the complex cation acts as a Brønsted acid to give a gelatinous white precipitate of triaaquatrihydroxyaluminium. This redissolves (another proton is lost and two waters are ejected) to give a colourless solution of the tetrahedral tetrahydroxyaluminate ion. (Only three moles of hydroxide are used.)
[Al(H2O)6]3+
  +  
4
NaOH(aq)
         
[Al(OH)4]–
  +  
4
Na+
  +  
6
H2O
Reactant Page Go To Go To
Hexaaquaaluminium complex ion     Reactions Using    Reactions Forming
Sodium hydroxide solution     Reactions Using    Reactions Forming
Tetrahydroxyaluminate ion     Reactions Using    Reactions Forming
Sodium ion     Reactions Using    Reactions Forming
Water     Reactions Using    Reactions Forming

Interaction, Reaction, Process defined as:
British A-Level Chemistry: A2
Change of Coordination Number
Dissolution: With Ionisation
Precipitation
Proton transfer: Brønsted reaction

© Mark R. Leach 1999 –

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