Q83E - Chemistry (OpenStax)

Question

Illustrate the amphoteric nature of aluminum hydroxide by citing suitable equations.

Step-by-Step Solution

Answer

Aluminum hydroxide is amphoteric, meaning it can behave as both an acid and a base in the right circumstances.

Step 1: Details of Aluminum

• Aluminum (Al) is a member of the periodic table's group IIIA, having a valence electron configuration of \({\rm{3}}{{\rm{s}}^{\rm{2}}}{\rm{3}}{{\rm{p}}^{\rm{1}}}\).
• Amphoteric substances have the ability to act as both a base and an acid.

Step 2: Find the balanced equations for cadmium burned in air

Under the appropriate conditions, the amphoteric character of \({\rm{Al}}{({\rm{OH}})_3}\)can be demonstrated by its behaviour as an acid or a basic.

 

When in the presence of an acid, such as \({\rm{HCl}},\;{\rm{Al}}{({\rm{OH}})_3}\), it works as a Bronsted-Lowry base, accepting the acid's protons. HCl protonates all three hydroxides in \({\rm{Al}}{({\rm{OH}})_3}\), resulting in the formation of \({\rm{AlC}}{{\rm{l}}_3}\)and water.

 

\({\rm{Al}}{({\rm{OH}})_3} + 3{\rm{HCl}} \to {\rm{AlC}}{{\rm{l}}_3} + 3{{\rm{H}}_2}{\rm{O}}\)

 

The electron deficient Al centre behaves as a Lewis acid in the presence of a base such as NaOH, accepting a pair of electrons to produce the equivalent salt.

 

\({\rm{Al}}{({\rm{OH}})_3} + {\rm{NaOH}} \to {\rm{NaAl}}{({\rm{OH}})_4}\)