Question

In the final step of the copper cycle, zinc, Zn \((s),\) is added to copper sulfate, \(\mathrm{CuSO}_{4}(a q)\) . Elemental copper appears as a solid. Explain what you think happens to the elemental zinc.

Short answer

Elemental zinc is oxidized and becomes part of zinc sulfate in solution.

Step-by-step solution

Understand the Reaction Components

In this reaction, zinc (Zn) is a solid metal and copper sulfate (CuSO₄) is in an aqueous solution. We are observing a single displacement reaction, where zinc will interact with copper ions in the solution.

Identify the Reaction Type

The reaction in question is a single replacement reaction where one metal replaces another in a compound. Here, zinc is more reactive than copper, so it can displace copper from copper sulfate.

Write the Chemical Equation

The balanced chemical equation for the reaction is: \[ \text{Zn} (s) + \text{CuSO}_4 (aq) \rightarrow \text{ZnSO}_4 (aq) + \text{Cu} (s) \]. Here, zinc replaces copper in the sulfate compound.

Explain the Role of Zinc

Zinc begins in its elemental form and during the reaction, it donates electrons to copper(II) ions in the solution. This results in zinc becoming oxidized to form zinc sulfate (ZnSO₄) while the copper ions gain electrons to form solid copper.

Conclusion on Elemental Zinc

Elemental zinc reacts with copper sulfate to become part of zinc sulfate. Therefore, the zinc ends up in the aqueous solution as zinc ions (Zn²⁺) bound to sulfate, while elemental copper is precipitated as a solid.

Key concepts

Zinc and Copper Reaction

When zinc is added to a copper sulfate solution, a fascinating transformation occurs due to a type of chemical reaction known as a single displacement reaction. In this scenario, zinc, which is more reactive than copper, displaces the copper from the solution. This results in the formation of zinc sulfate in the aqueous solution, while copper is liberated as a solid. The more reactive zinc metal essentially "takes over" the spot held by copper in the copper sulfate compound. This reaction illustrates the principle of reactivity series, where a more reactive metal can displace a less reactive metal from its compound.

During this reaction:

• Solid zinc is added to the solution.
• Copper sulfate in the solution dissociates into copper (Cu²⁺) ions and sulfate (SO₄²⁻) ions.
• Zinc displaces copper, forming zinc sulfate (ZnSO₄) in the solution and solid copper on the side.

This transformation highlights zinc's role as a robust displacing agent due to its higher reactivity compared to copper.

Solid Metal Reactions

Solid metal reactions, like the one between zinc and copper sulfate, demonstrate how solids can interact with other substances to form new compounds. These reactions are typically driven by the desire for elements to reach a more stable state with lower energy.

In the case of zinc and copper:

• Zinc starts as a solid metal, ready to engage with other elements.
• It reacts with the aqueous copper(II) sulfate solution.
• Through this interaction, copper is reduced to its solid elemental form, while zinc transitions to the aqueous phase as zinc sulfate.

This type of reaction is common in many industrial applications, such as in galvanization, where a thin layer of zinc is used to protect metals against corrosion.

Oxidation and Reduction

Oxidation and reduction reactions are a key concept to understand when analyzing the zinc and copper reaction. Commonly referred to as "redox" reactions, they involve the transfer of electrons between reactants.

In our example:

• Zinc undergoes oxidation, which means it loses electrons: \[ \text{Zn} (s) \rightarrow \text{Zn}^{2+} (aq) + 2\text{e}^- \]
• Copper ions in the copper sulfate solution are reduced as they gain electrons to form solid copper:\[ \text{Cu}^{2+} (aq) + 2\text{e}^- \rightarrow \text{Cu} (s) \]

These simultaneous processes ensure the conservation of charge and atoms during the chemical reaction. By recognizing these processes, students can grasp how elements change states and understand the shifts in oxidation numbers that define redox reactions.

Elemental Form Transformation

Elemental form transformation is a cornerstone of chemical reactions; it's the process where substances change their elemental forms. This is evident in the reaction between zinc and copper sulfate, highlighting both the power and intrigue of chemical interactions.

In this specific reaction:

• Zinc starts in its elemental metal form and transitions into a compound as zinc sulfate. It changes from a solid to an aqueous ion.
• Copper begins as a dissolved ion in the solution (part of copper sulfate) and is transformed into solid copper metal.

This swap emphasizes how substances can change their form and composition in response to their environment and interactions with other substances.

These transformations are not only fascinating on a theoretical level but also have real-world implications in fields like materials science and engineering, where the properties of substances are tailored for specific applications.