Question

Write the molecular, ionic, and net ionic equations for the reaction between \(\mathrm{NaCl}\) and \(\mathrm{AgNO}_{3}\) solutions that forms solid \(\mathrm{AgCl}\) leaving \(\mathrm{NaNO}_{3}\) in water.

Short answer

\(\mathrm{NaCl(aq) + AgNO}_{3}(aq) \rightarrow \mathrm{AgCl(s) + NaNO}_{3}(aq)\); Full ionic: \(\mathrm{Na}^{+}(aq) + \mathrm{Cl}^{-}(aq) + \mathrm{Ag}^{+}(aq) + \mathrm{NO}_{3}^{-}(aq) \rightarrow \mathrm{AgCl}(s) + \mathrm{Na}^{+}(aq) + \mathrm{NO}_{3}^{-}(aq)\); Net ionic: \(\mathrm{Ag}^{+}(aq) + \mathrm{Cl}^{-}(aq) \rightarrow \mathrm{AgCl}(s)\).

Step-by-step solution

Write the balanced molecular equation

Combine the reactant chemical formulas with their expected products and balance the equation. For the reaction between \(\mathrm{NaCl}\) and \(\mathrm{AgNO}_{3}\), the products will be \(\mathrm{AgCl}\), which is known to be insoluble and precipitates out of solution, and \(\mathrm{NaNO}_{3}\) which remains in solution. The balanced molecular equation is: \(\mathrm{NaCl(aq) + AgNO}_{3}(aq) \rightarrow \mathrm{AgCl(s) + NaNO}_{3}(aq)\).

Write the full ionic equation

Dissociate the soluble ionic compounds into their constituent ions. \(\mathrm{NaCl}\) and \(\mathrm{AgNO}_{3}\) are strong electrolytes and will dissociate completely in aqueous solution. The complete ionic equation is: \(\mathrm{Na}^{+}(aq) + \mathrm{Cl}^{-}(aq) + \mathrm{Ag}^{+}(aq) + \mathrm{NO}_{3}^{-}(aq) \rightarrow \mathrm{AgCl}(s) + \mathrm{Na}^{+}(aq) + \mathrm{NO}_{3}^{-}(aq)\).

Write the net ionic equation

Cancel out the spectator ions that appear on both sides of the full ionic equation to get the net ionic equation. Spectator ions do not participate in the actual chemical reaction. The spectator ions in this case are \(\mathrm{Na}^{+}\) and \(\mathrm{NO}_{3}^{-}\). The net ionic equation is: \(\mathrm{Ag}^{+}(aq) + \mathrm{Cl}^{-}(aq) \rightarrow \mathrm{AgCl}(s)\).

Key concepts

Molecular Equations

A molecular equation describes the chemical reaction using the formula of the reactants and products in their molecular forms. It provides an overview of the process without detailed information about the ionization. For instance, when sodium chloride (\(NaCl\)) reacts with silver nitrate (\(AgNO_{3}\)), the molecular equation would be \(NaCl(aq) + AgNO_{3}(aq) \rightarrow AgCl(s) + NaNO_{3}(aq)\). In this formula, \((aq)\) indicates that the compounds are in an aqueous solution, while \((s)\) denotes the formation of a solid, in this case, silver chloride (\(AgCl\)).

Ionic Equations

Ionic equations are more detailed than molecular equations and show the dissociation of strong electrolytes into their ions in an aqueous solution. This helps in identifying the actual participants in the chemical reaction. Dissociating the reactants of our example, we get \(Na^{+}(aq) + Cl^{-}(aq) + Ag^{+}(aq) + NO_{3}^{-}(aq)\). This representation makes it clearer that chemical reactions occur between ions in a solution. Full ionic equations help us visualize the charge interaction that leads to the formation of products.

Chemical Reaction

A chemical reaction is a process where reactants transform into products via breaking and forming of chemical bonds. This involves changes in the arrangement of electrons and can result in various forms of matter. In a reaction between \(NaCl\) and \(AgNO_{3}\), the \(Na^{+}\) ions swap places with \(Ag^{+}\) ions due to their different reactivities and solubilities, leading to the formation of solid \(AgCl\) and aqueous \(NaNO_{3}\). This type of chemical process exemplifies an exchange reaction or double displacement.

Spectator Ions

Spectator ions are present in the solution but do not participate in the actual chemical reaction. They remain unchanged and don't form part of the product. In our example, the \(Na^{+}\) and \(NO_{3}^{-}\) ions are spectators. Identifying spectator ions can simplify the overall reaction equation to a net ionic equation, focusing on the ions that participate in the formation of the precipitate.

Solubility

Solubility refers to the ability of a substance to dissolve in a solvent, often water for chemical reactions. The solubility of ionic compounds varies: some remain dissolved in water as ions, while others form a solid that precipitates from the solution. In the example of \(NaCl\) and \(AgNO_{3}\), \(NaNO_{3}\) remains soluble and hence stays in the aqueous phase, whereas \(AgCl\) has low solubility and precipitates out. Understanding solubility is crucial when predicting the outcome of chemical reactions and writing balanced equations.

Precipitation Reactions

Precipitation reactions occur when two soluble salts react in solution to form one insoluble product, called a precipitate, that settles out of the solution. In the reaction between \(NaCl\) and \(AgNO_{3}\), silver chloride (\(AgCl\)) is the precipitate. These reactions are fundamental in various fields including chemistry, environmental science, and medicine. Recognizing a precipitation reaction involves knowing the solubility rules, which predict whether a solid will form when solutions are mixed.