Problem 42 - Chemistry: The Central Science

Question

Because theoxide ion is basic, metal oxides react readily with acids. (a) Write the net ionic equation for the following reaction: $$ \mathrm{FeO}(s)+2 \mathrm{HClO}_{4}(a q) \longrightarrow \mathrm{Fe}\left(\mathrm{ClO}_{4}\right)_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l) $$ (b) Based on the equation in part (a), write the net ionic equation for the reaction that occurs between \(\mathrm{NiO}(s)\) and an aqueous solution of nitric acid.

Step-by-Step Solution

Answer

The net ionic equations for the given reactions are: a) \(\mathrm{FeO}(s) + 2 \mathrm{H^+}(a q) \longrightarrow \mathrm{Fe^{2+}}(a q)+\mathrm{H}_{2} \mathrm{O}(l)\) b) \(\mathrm{NiO}(s) + 2 \mathrm{H^+}(a q) \longrightarrow \mathrm{Ni^{2+}}(a q) + \mathrm{H}_{2} \mathrm{O}(l)\)

Step 1: Write the balanced equation for the given reaction

The given reaction is: $$ \mathrm{FeO}(s)+2 \mathrm{HClO}_{4}(a q) \longrightarrow \mathrm{Fe}\left(\mathrm{ClO}_{4}\right)_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l) $$ This equation is already balanced.

Step 2: Write the net ionic equation for the given reaction

To write the net ionic equation, we need to break down all the compounds into their individual ions (except for solid, liquid, and gaseous substances). FeO(s) is a solid and does not dissociate, so it remains as is: $$\mathrm{FeO}(s)$$ HClO4(aq) dissociates into its ions: $$2 \mathrm{H^+}(a q)+ 2\mathrm{ClO}_{4}^{-}(a q)$$ Fe(ClO4)2(aq) dissociates into its ions: $$ \mathrm{Fe^{2+}}(a q)+ 2\mathrm{ClO}_{4}^{-}(a q) $$ H2O(l) is a liquid and does not dissociate, so it remains as is: $$\mathrm{H}_{2} \mathrm{O}(l)$$ Now, we cancel out the spectator ions (ions that remain unchanged on both sides of the equation). In this case, the spectator ion is \(\mathrm{ClO}_{4}^{-}\). The net ionic equation is: $$ \mathrm{FeO}(s) + 2 \mathrm{H^+}(a q) \longrightarrow \mathrm{Fe^{2+}}(a q)+\mathrm{H}_{2} \mathrm{O}(l) $$

Step 3: Write the net ionic equation for the reaction between NiO and nitric acid

Using the net ionic equation from part (a) as a reference, we can write the net ionic equation for the reaction between \(\mathrm{NiO}(s)\) and an aqueous solution of nitric acid (HNO3): $$ \mathrm{NiO}(s) + 2 \mathrm{H^+}(a q) + 2 \mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{Ni^{2+}}(a q) + 2 \mathrm{NO}_{3}^{-}(a q) + \mathrm{H}_{2} \mathrm{O}(l) $$ Now, cancel the spectator ions (NO3-): The net ionic equation for the reaction between \(\mathrm{NiO}(s)\) and an aqueous solution of nitric acid is: $$ \mathrm{NiO}(s) + 2 \mathrm{H^+}(a q) \longrightarrow \mathrm{Ni^{2+}}(a q) + \mathrm{H}_{2} \mathrm{O}(l) $$

Key Concepts

Metal Oxides and Acids

When metal oxides interact with acids, a chemical reaction occurs primarily due to the basic nature of the metal oxide. Metal oxides, such as

• Iron(II) oxide (\(\mathrm{FeO}\)
• Nickel(II) oxide (\(\mathrm{NiO}\)

have \[\text{O}^{2-}\] ions which can accept protons (\(H^{+}\)) from acids. This proton acceptance results in the formation of water molecules while dissolving the oxide to form a metal salt For instance, in the reaction between \(\mathrm{FeO}\) and \(\mathrm{HClO}_{4}\) (perchloric acid), the oxide is transformed into iron perchlorate and water.Each reaction involves:

• Acid contribution of \(\mathrm{H}^{+}\) ions
• Neutralization by oxide ions
• Resultant formation of metal cations and water.

Understanding the interaction between metal oxides and acids is essential because it showcases how bases neutralize acids in solutions.

Chemical Reactions

A chemical reaction is a process that leads to the conversion of one set of chemical substances to another. In the context of metal oxides reacting with acids, these reactions are called "neutralization reactions." Neutralization reactions are essential because they show how acids and bases interact to form more neutral compounds.For example, the reaction \( \mathrm{FeO}(s) + 2 \mathrm{HClO}_{4}(aq) \rightarrow \mathrm{Fe}\left(\mathrm{ClO}_{4}\right)_{2}(aq) + \mathrm{H}_{2} \mathrm{O}(l) \) involves the reactants—a solid metal oxide and an aqueous acid—undergoing a transformation to products that include aqueous metal salts and water.Key points of these reactions include:

• Bonds breaking and forming between reactants and products
• Conservation of mass expressed in balanced equations
• Formation of compounds characterized by an exchange of ions.

Through these reactions, students are introduced to crucial concepts like balancing equations, stoichiometry, and types of reactions.

Ionic Dissociation

Ionic dissociation is the process in which an ionic compound separates into its individual ions in a solution. This breakdown is critical in the understanding of net ionic equations, which are simplified versions of chemical equations focusing solely on the molecules that change during the reaction.During dissociation:

• For acids such as \(\mathrm{HClO}_{4}\), it separates into \(\mathrm{H^{+}}\) and \(\mathrm{ClO}_{4}^{-}\)
• For metal salts like \(\mathrm{Fe(ClO}_{4})_{2}\), it dissociates into \(\mathrm{Fe^{2+}}\) and perchlorate ions.

Solids and liquids, such as \(\mathrm{FeO}\) and \(\mathrm{H}_{2} \mathrm{O}\), typically do not dissociate and remain intact in reactions.By understanding ionic dissociation, students can identify which parts of a reaction involve actual chemical changes and which ions are simply "spectators." This is crucial for constructing accurate net ionic equations.

Spectator Ions

Spectator ions are ions that exist in the same form on both the reactant and product sides of a chemical equation. These ions remain unchanged and do not participate in the chemical reaction itself.In net ionic equations, spectator ions are particularly significant because:

• They can be canceled from the complete ionic equation
• They help simplify the equation to focus on the actual chemical change occurring
• For example, \(\mathrm{ClO}_{4}^{-}\) in the reaction with \(\mathrm{FeO}\) and \(\mathrm{HClO}_{4}\), does not undergo any change and is therefore a spectator.

By removing these spectator ions, students can better understand the core chemical process and learn how to simplify complex reactions into more comprehensible expressions, capturing only the essence of the change.