Problem 37 - A Complete Resource Book in Chemistry for JEE Main

Question

An extremely hot copper wire reacts with steam to give (a) \(\mathrm{Cu}_{2} \mathrm{O}\) (b) \(\mathrm{CuO}_{2}\) (c) \(\mathrm{Cu}_{2} \mathrm{O}_{2}\) (d) \(\mathrm{CuO}\)

Step-by-Step Solution

Answer

(d) \(\mathrm{CuO}\) is formed.

Step 1: Understanding the Reaction

When a hot copper wire is exposed to steam, it undergoes an oxidation reaction where copper reacts with oxygen from the steam. This results in the formation of copper oxide as a primary product.

Step 2: Determine the Possible Oxides of Copper

Copper usually forms two oxides with oxygen: 1. Copper(I) oxide or cuprous oxide, which is \(\scriptstyle{\mathtt{Cu_{2}O}}\) 2. Copper(II) oxide or cupric oxide, which is \(\scriptstyle{\mathtt{CuO}}\). Other forms like \(\scriptstyle{\mathtt{CuO_{2}}}\) and \(\scriptstyle{\mathtt{Cu_{2}O_{2}}}\) are not standard oxides of copper.

Step 3: Analyzing Reactivity

Given the high temperature and steam as the reacting medium, copper is more likely to oxidize to form \(\scriptstyle{\mathtt{CuO}}\) due to the availability of ample oxygen in steam and favorable reaction conditions.

Step 4: Conclusion

Reviewing the standard reactions and the presented options, \(\scriptstyle{\mathtt{CuO}}\) is the most likely product formed when hot copper reacts with steam.

Key Concepts

Copper Oxides

Copper oxides are compounds formed by the combination of copper and oxygen. They occur in different forms depending on the oxidation state of the copper. The main types of copper oxides you'll encounter are:

• Copper(I) oxide (Cu₂O) - Also known as cuprous oxide, it is characterized by its reddish color. It occurs when copper is in the +1 oxidation state. This material is notable for its applications in fields such as semiconductors and antifouling paints.
• Copper(II) oxide (CuO) - Known as cupric oxide, it appears as a black solid due to copper being in the +2 oxidation state. This form is commonly found as a powder and used in the manufacture of pigments, batteries, and even in agriculture for fungicides.

While other forms like CuO₂ and Cu₂O₂ are mentioned sometimes, they are not typical or stable forms found in nature or standard reactions.
Copper oxides are important in various industrial applications and also play a significant role in educational chemistry settings due to their straightforward chemistry and the beautiful color changes they exhibit.

Oxidation Reaction

An oxidation reaction involves the loss of electrons by a substance. In the context of copper oxidizing, the metal copper loses electrons and subsequently reacts with oxygen to form an oxide.
Steam plays a crucial role in oxidation reactions as it provides both moisture and oxygen. When a heated copper wire comes into contact with steam, the oxygen in the water (a component of steam) interacts with the copper.

• Reactivity with Steam: The environment must be conducive for oxidation, and steam accomplishes this by offering moisture which is vital for facilitating the reaction.
• Elevated Temperature: High temperatures boost the reaction rate, driving copper to oxidize to Copper(II) oxide, giving off a black coloration.

In summary, oxidation is central to forming copper oxides when copper is subjected to steam. These reactions depict the transformation of metals into metal oxides through electron loss.

Chemical Reaction Analysis

Analyzing a chemical reaction involves understanding how reactants interact to form products. For copper reacting with steam, the major product observed is Copper(II) oxide (CuO). This conclusion is based on several factors:

• Product Stability: CuO is a stable product formed at high temperatures with sufficient oxygen supply derived from steam.
• Reaction Conditions: High temperatures favor the formation of CuO as opposed to other copper oxides. The presence of water further sustains the oxidation environment.

To confirm the likely outcome in reactions like these, chemists consider both thermodynamics and kinetics:

• Thermodynamics: Determines which products are energetically favorable.
• Kinetics: Involves the rate at which reactions proceed, influenced by temperature and concentration of reactants.

By evaluating these aspects, we understand why CuO is formed in this reaction. Such analysis is essential for accurately predicting the outcomes in chemical manufacturing and material science.