Problem 82 - A Complete Resource Book in Chemistry for JEE Main

Question

Brass is an alloy of (a) \(\mathrm{Cu}\) and \(\mathrm{Sn}\) (b) \(\mathrm{Ag}\) and \(\mathrm{Cu}\) (c) \(\mathrm{Cu}\) and \(\mathrm{Zn}\) (d) \(\mathrm{Sn}\) and \(\mathrm{Zn}\)

Step-by-Step Solution

Answer

Brass is an alloy of Cu and Zn, so the answer is (c).

Step 1: Understand Brass Composition

Brass is a metal alloy. An alloy is a mixture of two or more metals. Specifically, brass is known to be a mixture of copper (Cu) and zinc (Zn). This foundational understanding helps in identifying the components of brass.

Step 2: Analyze the Options Given

The problem provides four options for possible metal compositions of brass: (a) Copper (Cu) and tin (Sn), (b) Silver (Ag) and copper (Cu), (c) Copper (Cu) and zinc (Zn), and (d) Tin (Sn) and zinc (Zn). We need to check which combination correctly matches the known composition of brass.

Step 3: Identify the Correct Composition

Based on our knowledge that brass is composed of copper (Cu) and zinc (Zn), we find that option (c) Cu and Zn corresponds to the typical mixture that forms brass.

Key Concepts

Brass Composition

Brass is an interesting and practical metal alloy that people use in various everyday applications. An alloy is essentially a blend, typically of metals, that allows for the combination of different properties to create a more desirable material. For brass, the two core materials mixed together are copper (Cu) and zinc (Zn).
This mixture of metals results in an alloy with enhanced characteristics. For example, brass is known for its durability, corrosion resistance, and attractive appearance. Such properties make it particularly popular for decorative items, musical instruments, and fittings. Understanding the basic composition of brass helps us appreciate why it is such a versatile and widely used metal.
By knowing that brass is copper mixed with zinc, you can easily spot the difference when comparing it to other metals or alloys like bronze, which instead incorporates tin along with copper.

Copper and Zinc

Copper (Cu) and zinc (Zn) are metals with individual properties that can be fascinating. Copper is easily recognizable with its reddish-brown color and excellent electrical conductivity, making it a primary choice in electrical wiring.
On the other hand, zinc is a bluish-white, non-ferrous metal that provides a protective layer against corrosion when combined with other metals like copper in brass. Together, they form an alloy that boasts high durability and strength.
Once copper and zinc are combined to form brass, they lose some of their individual traits but gain a new set of improved qualities. This combination makes the resultant material suitable for manufacturing various items, from plumbing components to decorative pieces.

• Copper: good conductivity, reddish-brown color
• Zinc: corrosion-resistant, protective
• Together: strong, decorative, versatile

Alloy Identification

Identifying an alloy like brass is often the first step in understanding its applications and benefits. Knowing the composition of an alloy helps in determining the correct materials to use for specific purposes.
When trying to identify brass, look for certain visual cues and properties. Brass typically has a bright gold-like appearance due to its copper content. It's also softer than other metal composites, making it easy to machine or mold into different shapes.
Besides the physical characteristics, another effective way to identify an alloy is through chemical analysis. This can confirm the presence of copper and zinc, reinforcing its identity as brass. Recognizing these traits not only helps in distinguishing brass from other alloys, such as bronze or cupronickel, but also ensures its proper application in industries.

• Brightness: gold-like due to copper
• Softness: easy to machine
• Chemical analysis: confirms copper and zinc presence