Write a net ionic equation for the reaction with \(\mathrm{OH}^{-}\) by which (a) \(\mathrm{Sb}^{3+}\) forms a precipitate. (b) antimony(III) hydroxide dissolves when more \(\mathrm{OH}^{-}\) is added. (c) \(\mathrm{Sb}^{3+}\) forms a complex ion.

Chemical reactions are integral to understanding how substances interact to form new products. In a reaction, the reactants undergo a transformation leading to the formation of products. This can be illustrated through an equation showing reactants on one side and products on the other. A key aspect of chemical reactions is the conservation of mass, meaning the number of atoms for each element must be the same on both sides of the equation.

For example, when \(\mathrm{Sb}^{3+}\) reacts with \(\mathrm{OH}^-\) ions, they combine to produce a precipitate, \(\mathrm{Sb(OH)_3}\), in a precipitation reaction. The equation \(\mathrm{Sb^{3+}(aq) + 3OH^- (aq) \rightarrow Sb(OH)_3(s)}\) is balanced and shows the stoichiometry of reactants and product, adhering to the law of conservation of mass.

Solubility equilibrium is a fundamental concept when we talk about the dissolution or precipitation of substances. This dynamic equilibrium exists between the dissolved ions and the undissolved substance. If a substance's solubility limit is exceeded, excess solute will come out of the solution as a precipitate.

Understanding solubility is pivotal in predicting whether a precipitate will form in a reaction. For instance, when the \(\mathrm{Sb}^{3+}\) ions interact with a limited amount of \(\mathrm{OH}^-\) ions, a precipitate of \(\mathrm{Sb(OH)_3}\) forms because the product is not soluble in water. This is represented by the net ionic equation without any spectator ions, showing the direct transformation from reactants to the solid precipitate.

Complex ion formation involves the combination of simple ions to form a new, larger ion. This process is especially important in understanding chemical speciation in solutions. It often occurs when a metal ion binds to multiple ligands, which can be anions or neutral molecules, leading to the formation of a coordination complex.

For example, when more \(\mathrm{OH}^-\) is added to a solution-containing \(\mathrm{Sb(OH)_3}\), instead of forming a precipitate, it further reacts to form \(\mathrm{Sb(OH)_4^-}\), a complex ion. This process can be described as the dissolving of a precipitate to form a complex ion in solution, and the net ionic equation would show the conversion of the solid precipitate directly into the complex ion.