Question

Zinc-copper couple that can be used as a reducing agent is obtained by (a) zinc coated with copper (b) zinc and copper wires welded together (c) mixing zinc dust and copper gauze (d) copper coated with zinc

Short answer

The correct answer is (a) zinc coated with copper.

Step-by-step solution

Understanding the Question

The exercise asks for the method used to obtain a zinc-copper couple, which acts as a reducing agent. A zinc-copper couple is typically prepared by depositing metallic copper onto zinc particles.

Exploring the Options

We need to analyze each option: (a) Zinc coated with copper (b) Zinc and copper wires welded together (c) Mixing zinc dust and copper gauze (d) Copper coated with zinc The goal is to form a surface interaction where copper is deposited onto zinc.

Evaluating Option (a)

Option (a) suggests coating zinc with copper. This approach aligns with the method where metallic copper is deposited on zinc granules, forming an effective reducing agent.

Evaluating Option (b)

In option (b), welding zinc and copper wires together may not provide the intimate contact and surface reaction required since the core of the metals may not interact effectively.

Evaluating Option (c)

Option (c) involves mixing zinc dust and copper gauze. This physical mixture does not guarantee the deposition of copper on zinc, which is crucial for forming an active couple.

Evaluating Option (d)

Option (d) suggests coating copper with zinc, which is the reverse of what is generally done to prepare an effective zinc-copper couple. Usually, copper is deposited onto zinc.

Determining the Correct Answer

Based on the evaluations, option (a) "zinc coated with copper" is the method that successfully creates a zinc-copper couple by ensuring adequate copper deposition onto the zinc, enhancing its reducing properties.

Key concepts

Reducing Agent

A reducing agent is a substance that donates electrons to another substance, causing reduction. In chemistry, this involves the gain of electrons by the receiving substance. Reducing agents are typically found in reactions where a transfer of electrons takes place. They act by offering their electrons, effectively reducing another species in the reaction.
In the context of a zinc-copper couple, zinc primarily serves as the reducing agent. The presence of copper enhances zinc's ability to donate electrons more efficiently, facilitating reactions where substances are reduced. This enhanced electron movement is due to the surface interaction between zinc and copper, which helps achieve effective metal conduction of electrons.
Therefore, understanding reducing agents is key to grasping how certain reactions, such as those involving zinc-copper couples, result in the transformation of other chemicals. Recognizing their action can assist in predicting the outcomes of various chemical reactions.

Metal Coating

Coating metals is a common method used to modify the surface properties of base metals. In the case of a zinc-copper couple, the coating is pivotal as it enhances functionality. Here, copper is coated onto zinc to form a reactive interface.

• Importance of Coating: Coating improves surface properties such as corrosion resistance, electrical conductivity, and chemical reactivity.
• Methods: Different methods to coat metals include electroplating, where a metal layer is deposited using electrical currents, and deposition techniques that do not require currents.

When zinc is coated with copper, the outer copper layer reacts under specific conditions, allowing the zinc underneath to donate electrons more effectively. This allows the zinc-copper couple to act as an effective, efficient reducing agent in chemical reactions.
The quality of the coating, in terms of thickness and uniformity, significantly affects the overall reactivity and efficiency of the zinc-copper couple as a reducing agent.

Surface Interaction

Surface interaction refers to the way in which different materials interact at their surfaces, affecting properties like adhesion, reactivity, and electron transfer. In chemical processes, particularly those involving reducing agents, effective surface interaction is crucial.
For a zinc-copper couple, surface interaction ensures that zinc and copper can work together effectively. The copper, deposited on zinc, creates a critical interface that aids in the reduction processes.

• Electron Flow: Surface interaction between zinc and copper facilitates efficient electron transfer. This is what gives the zinc-copper couple its remarkable reducing properties.
• Reactivity: The interaction at the surface can enhance or diminish chemical reactivity, significantly impacting the behavior of the reduction process.

Understanding surface interactions aids in predicting and controlling the outcome of reactions involving metal couples. It is fundamental to the creation of compounds and materials that rely on surface-based mechanisms.

Deposition Process

The deposition process involves adding a material onto the surface of another substance. It is a critical step in creating effective zinc-copper couples used in various applications.
For a zinc-copper couple, deposition refers to putting copper onto zinc's surface. This provides the necessary environment for the two metals to interact beneficially.

• Chemical Deposition: This method uses chemical reactions to deposit materials. It is well-suited for creating a uniform layer of copper on zinc, necessary for a consistent reduction reaction.
• Physical Deposition: Physical methods might include vapor deposition, which can also achieve the desired coating results.

Choosing the right deposition technique is fundamental. The deposition quality directly influences the ability of the zinc-copper couple to function as a reducing agent. Effective deposition guarantees the necessary surface properties for chemical reactions, enhancing the conductivity and reactivity of the couple.