Answer
In acidic solution:
$- Sb(OH)_3(aq) + 3H_3O^+(aq) \lt -- \gt Sb^{3+}(aq) + 6H_2O(l)$
In basic solution:
$- Sb(OH)_3(aq) + OH^-(aq) \lt -- \gt [Sb(OH)_4]^-(aq)$
Work Step by Step
Metal hydroxides are amphoteric, and their behavior depends on the pH of the solution. If the solution is basic, it will react with the hydroxide ions, and if the solution is acidic, it will react with the hydronium ions.
The number of hydronium ions is equal to the number of hydroxide ions, and for the basic solution, the number of $OH^-$ molecules has to stabilize the orbitals of the metal.
