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 zinc-copper couple is obtained by option (c) mixing zinc dust and copper gauze.

Step-by-step solution

Understanding the Problem

The exercise asks us to identify how a zinc-copper couple, used as a reducing agent, is formed. This involves understanding how zinc-copper interactions create a useful reducing agent.

Option Analysis

Review each option provided: (a) Zinc coated with copper (b) Zinc and copper wires welded together (c) Mixing zinc dust and copper gauze (d) Copper coated with zinc. We need to determine which situation allows for the correct formation of the zinc-copper couple.

Evaluating Option (a)

Zinc coated with copper involves covering zinc with copper, but does not imply the necessary interaction between their surfaces that promotes reduction reactions.

Evaluating Option (b)

Zinc and copper wires welded together implies the two metals are in direct contact, possibly facilitating electron transfer, but this is not the traditional method for preparing a zinc-copper couple.

Evaluating Option (c)

Mixing zinc dust and copper gauze creates a physical mixture. The intimate contact and surface area provided by the dust and gauze enhance the reaction efficiency, which is ideal for creating a reducing agent.

Evaluating Option (d)

Copper coated with zinc reverses the typical roles of the metals and is not known to be an effective method for producing a zinc-copper couple.

Choosing the Best Option

After evaluating each possibility, option (c), mixing zinc dust and copper gauze, is the most likely process to yield a zinc-copper couple effective for reduction, due to the close contact and high surface area.

Key concepts

Reducing Agents

Reducing agents play a crucial role in chemical reactions by donating electrons to other substances, effectively reducing them. They are the opposite of oxidizing agents, which accept electrons. The main goal of a reducing agent is to decrease the oxidation state of a chemical species. For example, in the zinc-copper couple, zinc acts as the reducing agent.
- Zinc loses electrons readily to form zinc ions.
- This process facilitates the reduction of another substance in the reaction.
In real-world applications, reducing agents are vital in processes like metal extraction, chemical synthesis, and even photography. In the context of the zinc-copper couple, the reducing action arises due to the ability of zinc atoms to provide electrons to other substances in its vicinity.
Understanding the mechanics of reducing agents helps us appreciate why they are invaluable in various chemical processes.

Metal Interactions

The interactions between metals like zinc and copper are fascinating and pivotal for creating a zinc-copper couple. These interactions are primarily electronic and occur when the metals are in close proximity. When two metals come into contact, they can form galvanic cells or initiate redox reactions.
In the case of the zinc-copper couple:
- Zinc, which has a higher reactivity than copper, will tend to donate electrons.
- Copper can act as a catalyst in this setup by enhancing electron transfer.
The zinc can "push" electrons towards the copper, leading to the formation of a couple that is effective as a reducing agent. The significance lies in the migration of electrons between these metals, driven by differences in their reactivity and potential. By understanding these metal interactions, one can predict and manipulate the outcomes of various reactions, especially when forming reducing agents.

Surface Area in Chemical Reactions

Surface area is a critical factor in chemical reactions, especially when dealing with solid materials. It can significantly impact the rate at which reactions occur. A larger surface area allows for more exposure to reactants, leading to increased reaction efficiency. This is particularly true in the formation of the zinc-copper couple.
- Using zinc dust generates a high surface area due to its fine particles.
- Copper gauze provides a porous structure that further increases surface contact with zinc particles.
The enhanced surface area means that more atom-to-atom interactions can occur, facilitating faster and more efficient reactions. This characteristic is why mixing zinc dust with copper gauze is an effective way to create a zinc-copper couple. By maximizing surface area, the electrons have more pathways through which they can travel, making the chemical process smoother and more powerful. Understanding and optimizing surface area is crucial in industrial processes like catalysis and in designing effective batteries and sensors.