Question

Write the complete ionic equation for the reaction of \(\mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}(\mathrm{aq})\) and \(\mathrm{Sr}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})\). You may have to consult the solubility rules.

Short answer

The complete ionic equation illustrates ion dissociation and the formation of insoluble SrSO₄.

Step-by-step solution

Identify Reactants and Products

The reactants are \( \text{Fe}_2(\text{SO}_4)_3(\text{aq}) \) and \( \text{Sr(NO}_3)_2(\text{aq}) \). To predict products, consider possible combinations: \( \text{SrSO}_4 \) and \( \text{Fe(NO}_3)_3 \). According to solubility rules, \( \text{SrSO}_4 \) is insoluble and will form a precipitate, while \( \text{Fe(NO}_3)_3 \) remains soluble in solution.

Write Molecular Equation

Write the molecular equation for the reaction: \[ \text{2 Fe}_2(\text{SO}_4)_3(\text{aq}) + 3 \text{Sr(NO}_3)_2(\text{aq}) \rightarrow 3 \text{SrSO}_4(\text{s}) + \text{2 Fe(NO}_3)_3(\text{aq}) \]. This equation involves balancing the sulfate \((\text{SO}_4^{2-})\) and nitrate \((\text{NO}_3^{-})\) ions.

Write Complete Ionic Equation

Convert the balanced molecular equation into a complete ionic equation. Begin by dissociating all soluble compounds: \[ \text{2 Fe}^{3+}(\text{aq}) + 3 \text{SO}_4^{2-}(\text{aq}) + 3 \text{Sr}^{2+}(\text{aq}) + 6 \text{NO}_3^-(\text{aq}) \rightarrow 3 \text{SrSO}_4(\text{s}) + 2 \text{Fe}^{3+}(\text{aq}) + 6 \text{NO}_3^-(\text{aq}) \].

Key concepts

Solubility Rules

Solubility rules help predict whether a compound will dissolve in water or form a precipitate. In the context of chemical reactions, these rules are vital for identifying which products remain aqueous and which form solid precipitates. For example, most nitrates (\( ext{NO}_3^- \)) are soluble, meaning they will dissolve in water and not form a solid. However, when it comes to sulfates (\( ext{SO}_4^{2-} \)), there are exceptions. Compounds like \( ext{SrSO}_4 \) are typically insoluble, meaning they will not dissolve and instead form a solid precipitate.
Using solubility rules can thus indicate whether or not a product will be seen as a solid in the reaction, as is the case with the formation of \( ext{SrSO}_4 \) from the reaction between \( ext{Fe}_2( ext{SO}_4)_3( ext{aq}) \) and \( ext{Sr(NO}_3)_2( ext{aq}) \). Observing these guidelines ensures clarity on the state of each compound in the complete ionic equation.

Molecular Equation

A molecular equation provides an overall representation of a chemical reaction, displaying each of the reactants and products in their complete, molecular form. In our particular example involving \( ext{Fe}_2( ext{SO}_4)_3( ext{aq}) \) and \( ext{Sr(NO}_3)_2( ext{aq}) \), the molecular equation shows the interaction between these two reactants:

• \( ext{2 Fe}_2( ext{SO}_4)_3( ext{aq}) + 3 ext{Sr(NO}_3)_2( ext{aq}) \)
• \( ightarrow 3 ext{SrSO}_4( ext{s}) + 2 ext{Fe(NO}_3)_3( ext{aq}) \)

Each compound here is depicted as a whole unit, rather than breaking down into individual ions. The molecular equation is key in predicting the type of chemical reactions that occur, specifically identifying which compounds combine and what new compounds form, such as the solid precipitate \( ext{SrSO}_4 \). It also helps in balancing chemical equations by ensuring the number of each kind of atom is equal on both sides.

Ionic Equations

Ionic equations break down soluble compounds into their respective ions, providing a more detailed picture of the reaction process. The complete ionic equation lists all ions present in the reaction, showcasing which ions interact and which remain unchanged in solution. Let's see how this applies:
For this reaction, soluble compounds like \( ext{Fe}_2( ext{SO}_4)_3( ext{aq}) \) and \( ext{Sr(NO}_3)_2( ext{aq}) \) break apart into their ions:

• \( ext{2 Fe}^{3+}( ext{aq}) + 3 ext{SO}_4^{2-}( ext{aq}) \)
• \( + 3 ext{Sr}^{2+}( ext{aq}) + 6 ext{NO}_3^-( ext{aq}) \)
• \( ightarrow 3 ext{SrSO}_4( ext{s}) + 2 ext{Fe}^{3+}( ext{aq}) + 6 ext{NO}_3^-( ext{aq}) \)

The complete ionic equation highlights the formation of \( ext{SrSO}_4 \), as these ions combine to form a solid precipitate. It also identifies spectator ions, like nitrate \( ext{NO}_3^- \), which do not change and are present on both sides of the equation.

Chemical Reactions

Chemical reactions involve the rearrangement of atoms to form new substances. During such processes, reactants interact to form products, as seen in the reaction of \( ext{Fe}_2( ext{SO}_4)_3( ext{aq}) \) and \( ext{Sr(NO}_3)_2( ext{aq}) \). The key components here involve identifying reactants, predicting products, and understanding their physical states, guided by principles like solubility rules.
There are different types of chemical reactions, such as:

• Synthesis reactions, where simple substances combine to form more complex ones.
• Decomposition reactions, breaking down complex molecules into simpler parts.
• Double replacement reactions, which occur here, where parts of two compounds switch places, leading to new products.

Understanding these types allows students to predict outcomes of reactions and write chemical equations effectively. In this scenario, identifying \( ext{SrSO}_4 \) as a precipitate is crucial for determining the course and balance of the reaction.