Problem 150 - A Complete Resource Book in Chemistry for JEE Main

Question

vSilver is a soft metal. It is hardened by alloying it wi small amounts of (a) \(\mathrm{Cu}\) (b) \(\mathrm{Fe}\) (c) \(\mathrm{Ni}\) (d) \(\mathrm{Sn}\)

Step-by-Step Solution

Answer

Silver is hardened by alloying it with small amounts of copper (Cu).

Step 1: Understanding Alloying

Alloying is the process of mixing a metal with other elements to improve its properties, such as strength or hardness. When silver is alloyed with certain metals, it becomes harder and more durable.

Step 2: Identify Suitable Alloying Elements

Silver can be alloyed with different metals to enhance its hardness. We need to determine which of the given options are typically used to harden silver. Copper (Cu), Nickel (Ni), Iron (Fe), and Tin (Sn) are common alloying elements, but not all are suitable for hardening silver.

Step 3: Evaluate Options

Among the options provided, copper (Cu) is commonly used to alloy with silver to create sterling silver, which is a harder form of silver. The other elements like iron (Fe), nickel (Ni), and tin (Sn) are not traditionally known for hardening silver.

Step 4: Select the Correct Element

Based on typical practices, when silver is alloyed with copper, it becomes harder, making copper the correct choice from the given options.

Key Concepts

Silver

Silver is a precious metal renowned for its lustrous sheen and soft texture. Though beautiful, its softness makes it less practical for everyday use without alteration. This softness means silver can easily bend, scratch, or wear out. Despite these limitations, silver sees widespread use in jewelry, coins, and cutlery because of its stunning appearance. However, its applications can extend further when alloyed.

By combining silver with other metals, we improve its hardness and durability while maintaining its attractive surface. This process is known as alloying. Among its properties, silver exhibits high electrical conductivity and antimicrobial properties, which is why it's also used in electronics and medicine.

Hardening Metals

Hardening metals through alloying enhances their strength and wear resistance. This technique involves blending a primary metal with one or more additional elements. These elements usually have distinct atomic arrangements that can reinforce the lattice structure of the original metal.

When metals like silver are too soft for specific uses, alloying them with harder elements increases their tensile strength and decreases malleability. Techniques like solution hardening and precipitation hardening are often applied during this process.

• Solution Hardening: Involves dissolving alloying elements into the base metal, resulting in a harder metal structure.
• Precipitation Hardening: Uses age hardening techniques to form new phases within the metal, further enhancing its strength.

These methods are crucial for creating metals that can withstand daily wear and tear.

Copper Alloy

Copper alloys are particularly effective when it comes to modifying a base metal's properties. Copper is an ideal element for alloying with silver because it enhances hardness without drastically changing the silver's color or other desirable properties. A popular result is sterling silver, which consists of approximately 92.5% silver and 7.5% copper.

Sterling silver is a prime example of a copper alloy, balancing the aesthetic appeal of silver with the robustness introduced by copper. This alloy retains the luster of silver but provides the practical strength needed for jewelry and other valuable items.

Alloying processes not only improve mechanical properties but also the thermal and electrical conductivity of the resultant material, making these alloys versatile and practical for various applications beyond jewelry, including electrical components and musical instruments.