Question

Complete and balance each equation. If no reaction occurs, write NO REACTION. a. \(\operatorname{NaNO}_{3}(a q)+\mathrm{KCl}(a q) \longrightarrow\) b. \(\mathrm{NaCl}(a q)+\mathrm{Hg}_{2}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{2}(a q) \longrightarrow\) c. \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}(a q)+\mathrm{Sr} \mathrm{Cl}_{2}(a q) \longrightarrow\) d. \(\mathrm{NH}_{4} \mathrm{Cl}(a q)+\mathrm{AgNO}_{3}(a q) \longrightarrow\)

Short answer

a. NO REACTIONb. 2 NaCl(aq) + Hg2(C2H3O2)2(aq) \rightarrow 2 NaC2H3O2(aq) + Hg2Cl2(s)c. (NH4)2SO4(aq) + SrCl2(aq) \rightarrow 2 NH4Cl(aq) + SrSO4(s)d. NH4Cl(aq) + AgNO3(aq) \rightarrow NH4NO3(aq) + AgCl(s)

Step-by-step solution

- Determine the solubility of the reaction products

Use a solubility table to determine if any of the potential products of each reaction are insoluble in aqueous solution. Insoluble products indicate a possible chemical reaction. For each equation, predict the potential products by exchanging the cations and anions of the reactants.

- Analyze the potential products

Determine if the predicted products are soluble or insoluble. Soluble compounds remain in solution and do not form a precipitate, whereas insoluble compounds will form a solid precipitate, indicating that a reaction has occurred.

- Write the complete balanced equation or NO REACTION

Based on the solubility of the products, write the complete balanced chemical equation with state symbols (s for solid, aq for aqueous). If no insoluble product is formed, write NO REACTION.

- Apply the process to each given reaction

Repeat Steps 1 to 3 for each of the given equations a to d.

Key concepts

Solubility Rules

Understanding the solubility rules is crucial for predicting the outcome of chemical reactions, especially when it comes to precipitation reactions. Solubility rules help us determine which ionic compounds are soluble and which are not when dissolved in water.

Soluble compounds dissolve in water and are usually not part of a reaction's net ionic equation. In contrast, compounds that are considered insoluble form a precipitate, or a solid, when in solution with another ionic compound. These rules are not without exceptions, but they give us a good starting point for predicting solubility. For example, the rule that 'all sodium, potassium, and ammonium salts are soluble' would mean that in the presence of these ions, we would expect the products to remain in solution, generally leading to no visible reaction.

Precipitation Reactions

A precipitation reaction is a type of chemical reaction where two solutions, each containing soluble salts, are mixed together resulting in the formation of an insoluble salt that precipitates out of the solution. This reaction can be predicted using the solubility rules. If the product of an exchange reaction between two ionic compounds is insoluble, it will precipitate from the solution.

For example, when solutions of \texttt{AgNO3} and \texttt{NaCl} are mixed, \texttt{AgCl}, an insoluble compound, forms as a precipitate. This reaction is represented by the chemical equation: \( \texttt{AgNO3 (aq) + NaCl (aq) \rightarrow AgCl (s) + NaNO3 (aq)} \). The solid silver chloride (\texttt{AgCl}) is the precipitate, easily observed as it forms.

Balancing Chemical Equations

The process of balancing chemical equations involves making sure that the same number of each type of atom appears on both sides of the equation. This adheres to the Law of Conservation of Mass, which states that matter cannot be created or destroyed. To balance an equation, we adjust the coefficients, the numbers that appear before the chemical formulas, without altering the actual formulas of the compounds.

For instance, if we have the unbalanced equation \( \texttt{Fe + O2 \rightarrow Fe2O3} \) we notice that there are an unequal number of iron (Fe) and oxygen (O) atoms on both sides. To balance the equation, we might write it as \( \texttt{4Fe + 3O2 \rightarrow 2Fe2O3} \) which now has four iron atoms and six oxygen atoms on both sides of the equation, fulfilling the requirement for balance.

Exchange Reactions

An exchange reaction, also known as a double replacement reaction, is a type of chemical reaction where the cations and anions of two different molecules switch places, resulting in the formation of two new compounds. The general formula can be represented as \( \texttt{AB + CD \rightarrow AD + BC} \), where \texttt{A} and \texttt{C} are cations, and \texttt{B} and \texttt{D} are anions.

In many cases, exchange reactions result in the formation of at least one insoluble product, thus leading to a precipitation reaction. To predict the products of an exchange reaction, you identify the possible combinations of the cations and anions and apply the solubility rules to determine if any insoluble compounds form. For example, in an exchange reaction between \texttt{Na2SO4} and \texttt{BaCl2}, barium sulfate (\texttt{BaSO4}) precipitates because it's insoluble, while sodium chloride (\texttt{NaCl}) remains in solution.