Problem 47 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is formed when cupric oxide reacts with glucose? (a) \(\mathrm{CuCHO}\) (b) \(\mathrm{CuO}\) (c) \(\mathrm{Cu}_{2} \mathrm{O}\) (d) \(\mathrm{C}_{5} \mathrm{H}_{11} \mathrm{O}_{6}\)

Step-by-Step Solution

Answer

Cupric oxide produces Cuprous oxide (\(\text{Cu}_2\text{O}\)); answer (c).

Step 1: Understand the Reaction

Cupric oxide \((\text{CuO})\) reacts with glucose \((\text{C}_6\text{H}_12\text{O}_6)\) in a reduction-oxidation reaction. In this process, glucose acts as a reducing agent and reduces \text{CuO}\ to another copper oxide while it gets oxidized to another compound.

Step 2: Identify the Chemistry Involved

Cupric oxide \((\text{CuO})\) gets reduced to cuprous oxide \((\text{Cu}_2\text{O})\) when it reacts with glucose. Glucose itself is oxidized into gluconic acid or heat forms other products such as water, depending on conditions.

Step 3: Determine the Product Formed

From the reaction, the cupric oxide \((\text{CuO})\) is reduced to cuprous oxide \((\text{Cu}_2\text{O})\). Therefore, the correct answer corresponds to \(\text{Cu}_2\text{O}\).

Step 4: Verify the Choice

Among the given options, \(\text{Cu}_2\text{O}\) aligns with the predicted product from the reduction of cupric oxide by glucose. Hence, option (c) is the correct answer.

Key Concepts

Cupric Oxide

Cupric oxide, known by its chemical formula \( \text{CuO} \), is a black solid that naturally occurs in the mineral tenorite. It is an important compound in chemistry, widely used in various applications such as pigments, ceramics, and batteries. One of the key features of cupric oxide is its ability to participate in reduction-oxidation (redox) reactions.

In a redox reaction, one substance is oxidized (loses electrons), and another is reduced (gains electrons). Cupric oxide can act as an oxidizing agent, meaning it accepts electrons from other substances during the reaction. This makes it a good candidate for being reduced to other copper compounds like cuprous oxide. When cupric oxide reacts in a redox environment with glucose, it undergoes a chemical transformation, showcasing its redox properties.

• Occurs as a black solid in nature.
• Plays a significant role in redox reactions, acting as an oxidizing agent.
• Versatile compound, used in pigments, ceramics, and batteries.

Glucose

Glucose, with the formula \( \text{C}_6\text{H}_{12}\text{O}_6 \), is a simple sugar and an essential carbohydrate in biology. Acting as a primary source of energy, glucose is crucial for cells in plants, animals, and humans. But beyond its biological significance, glucose also plays a pivotal role in chemical reactions.

When glucose participates in redox reactions, it often acts as a reducing agent. This means glucose donates electrons to other substances, oxidizing itself in the process. In the reaction with cupric oxide, glucose is oxidized, usually transforming into gluconic acid (or other products under specific conditions). This extract of energy and transformation highlight glucose's magnificent capacity in chemical reactions.

• Simple sugar vital for energy in living organisms.
• Can act as a reducing agent, donating electrons in reactions.
• Transforms into gluconic acid when oxidized.

Cuprous Oxide

Cuprous oxide \( \text{Cu}_2\text{O} \) is a red or reddish-brown solid that derives from the reduction of cupric oxide. It is less common in natural minerals compared to cupric oxide, but it plays a crucial role in various applications, such as fungicides, antifouling paints, and solar cells. In redox chemistry, cuprous oxide is the reduced form of copper oxide.

When cupric oxide is reduced by a substance like glucose, it gains electrons and forms cuprous oxide. This reduction exhibits the reactivity and adaptability of copper in various oxidation states. The transformation from \( \text{CuO} \) to \( \text{Cu}_2\text{O} \) is a classical occurrence in redox reactions, and demonstrates the practical implications of these inorganic substances in industrial processes.

• Appears as a red or reddish-brown solid.
• Formed by the reduction of cupric oxide (\( \text{CuO} \)).
• Used in fungicides, antifouling paints, and solar technologies.