Problem 40 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following metal is present in brass, bronze and german silver? (a) \(\mathrm{Mg}\) (b) \(\mathrm{Cu}\) (c) \(\mathrm{Al}\) (d) \(\mathrm{Na}\)

Step-by-Step Solution

Answer

The metal present in brass, bronze, and german silver is Copper (Cu).

Step 1: Identify Components of Brass

Brass is composed primarily of copper (Cu) and zinc (Zn). Therefore, copper is present in brass.

Step 2: Identify Components of Bronze

Bronze is generally made from copper (Cu) and tin (Sn). This means that copper is also a component of bronze.

Step 3: Identify Components of German Silver

German Silver, also known as nickel silver, contains copper (Cu), nickel (Ni), and zinc (Zn). Thus, copper is present in German Silver as well.

Step 4: Conclusion

Since copper (Cu) is present in all three—brass, bronze, and german silver—the answer is option (b) \( \mathrm{Cu} \).

Key Concepts

Brass composition

Brass is a popular metal alloy widely used for its appealing golden hue and resistance to corrosion. It primarily consists of two main components:

• Copper (Cu): The major component which can range from 55% to 90% depending on the specific type of brass.
• Zinc (Zn): This metal makes up the rest of the composition, typically between 10% and 45%.

The proportions of copper and zinc can vary, allowing brass to have different properties suited for various applications.
Brass is known for its malleability, high durability, and acoustic properties, making it ideal for musical instruments, decorative items, and fittings. Furthermore, its low friction makes it suitable for locks and gears.

Bronze composition

Bronze is an ancient alloy with a rich history of use dating back thousands of years. Its composition primarily involves:

• Copper (Cu): This is the predominant metal in bronze, usually accounting for about 88% of the alloy.
• Tin (Sn): The second component, which typically makes up around 12%.

Sometimes, manufacturers may include small amounts of phosphorus, manganese, aluminium, or silicon to enhance specific properties of the alloy.
One of the notable characteristics of bronze is its excellent resistance to corrosion, especially in seawater, which makes it ideal for boat fittings and sculptures. Its combination of toughness and wear resistance also finds applications in tools, machine parts, and architectural accents.

German silver composition

Despite its name, German silver doesn't actually contain any silver. It's an alloy known for its silvery appearance and is composed mostly of:

• Copper (Cu): This makes up a substantial portion, around 60%.
• Nickel (Ni): Contributing to the hardness and corrosion resistance, nickel is usually around 20% of the mixture.
• Zinc (Zn): Completing the composition, zinc often constitutes about 20%.

This alloy is known for its strength, resilience to tarnishing, and bright finish. German silver is commonly used in the manufacturing of musical instruments, cutlery, and jewelry. Due to its attractive appearance and strength, it is also popular for crafting various decorative items.

Metal components

Alloys like brass, bronze, and German silver are compounded from various metals to achieve specific desired traits. Here are some general reasons why different metals are used in alloys:

• Copper (Cu): Provides high thermal and electrical conductivity, and is used widely for its ductility and antibacterial properties.
• Zinc (Zn): Offers corrosion resistance and improves strength.
• Tin (Sn): Best known for its ability to prevent corrosion.
• Nickel (Ni): Adds to the hardness and corrosion resistance of an alloy.

The combination of these metals allows for tailored properties such as improved strength, flexibility, or resistance to environmental factors, making these alloys invaluable in various industries from architecture to electronics.

Copper in alloys

Copper is a critical element used in many alloys. As seen in brass, bronze, and German silver, copper is a significant component, contributing to:

• Conductivity: Copper is well-known for its excellent electrical and thermal conductivity, making it indispensable in wiring and electronics.
• Corrosion resistance: This property allows copper-based alloys to be used in environments where rust and deterioration are concerns, such as marine applications.
• Ductility: Copper's flexibility makes it easy to work with, which is essential for forming intricate shapes.

Alongside these attributes, copper lends a richness in color to alloys, guiding aesthetic choices in design and sculpture. Its fundamental role in various alloys underscores the vast versatility and importance of copper in both ancient and modern technological advancements.