Question

Predict the products of each reaction and write balanced complete ionic and net ionic equations for each. If no reaction occurs, write NO REACTION. (a) \(\mathrm{NaI}(a q)+\mathrm{Hg}_{2}\left(\mathrm{NO}_{3}\right)_{2}(a q) \longrightarrow\) (b) \(\mathrm{HClO}_{4}(a q)+\mathrm{Ba}(\mathrm{OH})_{2}(a q) \longrightarrow\) (c) \(\mathrm{Li}_{2} \mathrm{CO}_{3}(a q)+\mathrm{NaCl}(a q) \longrightarrow\) (d) \(\mathrm{HCl}(a q)+\mathrm{Li}_{2} \mathrm{CO}_{3}(a q)\)

Short answer

(a) Net ionic: \(\mathrm{Hg}_2^{2+}(aq) + 2 \mathrm{I}^-(aq) \longrightarrow \mathrm{Hg}_2\mathrm{I}_2(s)\). (b) Net ionic: \(2 \mathrm{H}^+(aq) + 2 \mathrm{OH}^-(aq) \longrightarrow 2 \mathrm{H}_2\mathrm{O}(l)\). (c) NO REACTION. (d) Net ionic: \(\mathrm{H}^+(aq) + \mathrm{CO}_3^{2-}(aq) \longrightarrow \mathrm{H}_2\mathrm{O}(l) + \mathrm{CO}_2(g)\).

Step-by-step solution

Predict the products of NaI + Hg2(NO3)2

Reacting sodium iodide (NaI) with mercury(I) nitrate (Hg2(NO3)2) may lead to a double replacement reaction. Since mercury(I) compounds are typically written as Hg2^2+, the predicted products are mercury(I) iodide (Hg2I2) and sodium nitrate (NaNO3).

Write the balanced complete ionic equation for NaI + Hg2(NO3)2

Write out all aqueous compounds as ions as they exist in solution, keeping solid or precipitated or weakly ionized compounds intact, to give the complete ionic equation: \[2 \mathrm{Na}^+(aq) + 2 \mathrm{I}^-(aq) + \mathrm{Hg}_2^{2+}(aq) + 2 \mathrm{NO}_3^-(aq) \longrightarrow \mathrm{Hg}_2\mathrm{I}_2(s) + 2 \mathrm{Na}^+(aq) + 2 \mathrm{NO}_3^-(aq)\]

Write the net ionic equation for NaI + Hg2(NO3)2

Cancel out the spectator ions that do not change during the reaction to obtain the net ionic equation: \[\mathrm{Hg}_2^{2+}(aq) + 2 \mathrm{I}^-(aq) \longrightarrow \mathrm{Hg}_2\mathrm{I}_2(s)\]

Predict the products of HClO4 + Ba(OH)2

Reacting perchloric acid (HClO4) with barium hydroxide (Ba(OH)2) will result in a neutralization reaction producing water (H2O) and barium perchlorate (Ba(ClO4)2).

Write the balanced complete ionic equation for HClO4 + Ba(OH)2

\[2 \mathrm{H}^+(aq) + 2 \mathrm{ClO}_4^-(aq) + \mathrm{Ba}^{2+}(aq) + 2 \mathrm{OH}^-(aq) \longrightarrow 2 \mathrm{H}_2\mathrm{O}(l) + \mathrm{Ba}^{2+}(aq) + 2 \mathrm{ClO}_4^-(aq)\]

Write the net ionic equation for HClO4 + Ba(OH)2

Remove the spectator ions to find the net ionic equation: \[2 \mathrm{H}^+(aq) + 2 \mathrm{OH}^-(aq) \longrightarrow 2 \mathrm{H}_2\mathrm{O}(l)\]

Predict the products of Li2CO3 + NaCl

Lithium carbonate (Li2CO3) reacts with sodium chloride (NaCl), but since no precipitate forms, nor is there gas release or water production, no reaction occurs.

Predict the products of HCl + Li2CO3

When hydrochloric acid (HCl) reacts with lithium carbonate (Li2CO3), a neutralization reaction occurs, forming water (H2O), carbon dioxide (CO2), and lithium chloride (LiCl).

Write the balanced complete ionic equation for HCl + Li2CO3

\[2 \mathrm{H}^+(aq) + 2 \mathrm{Cl}^-(aq) + 2 \mathrm{Li}^+(aq) + \mathrm{CO}_3^{2-}(aq) \longrightarrow 2 \mathrm{Li}^+(aq) + 2 \mathrm{Cl}^-(aq) + \mathrm{H}_2\mathrm{O}(l) + \mathrm{CO}_2(g)\]

Write the net ionic equation for HCl + Li2CO3

Eliminate the spectator ions to find the net ionic equation: \[\mathrm{H}^+(aq) + \mathrm{CO}_3^{2-}(aq) \longrightarrow \mathrm{H}_2\mathrm{O}(l) + \mathrm{CO}_2(g)\]

Key concepts

Chemical Reactions

In the realm of chemistry, a chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Classically, they involve changes that include the motion of electrons in the forming and breaking of chemical bonds. Among the different types, one paramount reaction type is the double replacement reaction, which often occurs in aqueous solutions. Here, ions exchange partners resulting in the formation of two new compounds, typically when one of the products is insoluble, a gas, or a weak electrolyte.

Understanding chemical reactions requires a grasp of reactants, products, the conservation of mass, and the need to balance equations. For example, when NaI reacts with Hg₂(NO₃)₂, a double replacement reaction ensues, leading to the formation of Hg₂I₂ and NaNO₃. The balanced equation ensures that the same number of atoms for each element is present on both the reactant and product sides, upholding the law of conservation of mass.

Solubility Rules

The solubility rules are a set of guidelines that help predict whether an ionic compound will dissolve in water, an essential aspect in writing net ionic equations. These rules indicate, for example, that compounds formed with Group 1 elements like Na⁺ are usually soluble, and so, sodium nitrate (NaNO₃) dissolves in water. Similarly, nitrates (NO₃^-) are universally soluble.

However, exceptions exist, such as when dealing with compounds like mercury(I) iodide (Hg₂I₂) which is insoluble in water, precipitating out of the solution. Recognizing these solubility trends is paramount when predicting products of reactions, as with the exercise. Nailing down these rules does immense favors to students, as it allows them to correctly identify the substances that will precipitate, remain in solution, or react to form a gas or weakly ionized compound.

Double Replacement Reactions

The double replacement reaction is a specific type of chemical reaction where two compounds exchange ions to form two new compounds. They are often performed in aqueous solution and require one of the products to be insoluble, gas, or a weak electrolyte to drive the reaction forward.

In the case of HClO₄ reacting with Ba(OH)₂, for instance, the H⁺ ion from the acid swaps places with the Ba²⁺ ion from the base, leading to the formation of water (H₂O) and soluble barium perchlorate (Ba(ClO₄)₂). Here, the neutralization reaction between an acid and a base is a classic example of double replacement. Our ability to predict these reactions hinges upon understanding the nature of the reactants, solubility rules, and the expected properties of the products.