Problem 39 - Chemistry The Molecular Science

Question

Describe why other metals are added to silver and gold.

Step-by-Step Solution

Answer

Metals are added to silver and gold to improve hardness, durability, suitability for practical uses, and cost efficiency.

Step 1: Understanding Pure Metals

Gold and silver, when in their pure forms, are relatively soft and malleable. This means they can be easily shaped and molded, but also that they can be bent or scratched during everyday use if not combined with other elements.

Step 2: Enhancing Physical Properties

Alloying gold and silver with other metals, such as copper or nickel, increases their hardness and durability. This enhancement allows the metals to be used more effectively in practical applications, such as jewelry and coins, which require metals that don't easily deform or damage.

Step 3: Practical Applications of Alloys

By mixing metals such as copper into silver and gold, we create alloys that are more suitable for specific purposes. For example, sterling silver, an alloy of silver and copper, is commonly used in jewelry because it is both hard and visually appealing.

Step 4: Cost Efficiency

Alloying can also make use of less expensive metals to produce a valuable final product. By adding less expensive metals to silver or gold, the overall cost of the material is decreased while still maintaining an acceptable level of quality.

Key Concepts

Gold alloys

Gold is a precious metal valued for its beauty and rarity. When used in its pure form, gold is soft and can easily be shaped or damaged. To make it suitable for everyday use, other metals are added to create gold alloys. The addition of metals like copper and silver boosts its strength and durability.

Gold alloys are commonly categorized by their karat, which indicates the proportion of pure gold in the alloy. For example, 18 karat gold is 75% pure gold, mixed with 25% other metals. These additives not only enhance the physical properties of gold but also affect its color and cost.

• Color variations: By altering the mix of metals, gold alloys can be made in different colors such as white gold (mixed with palladium or nickel), rose gold (mixed with copper), and green gold (mixed with silver).
• Cost efficiency: Gold alloys tend to be less expensive than pure gold, making them an attractive choice for jewelry and ornaments.

Gold alloys are used in applications ranging from jewelry to electronics, where gold's conductivity is valued, along with its enhanced resilience.

Silver alloys

Like gold, pure silver is soft and not practical for items that are subject to wear and tear. To improve its utility, silver is often alloyed with metals such as copper. The most well-known silver alloy is sterling silver, which consists of 92.5% silver and 7.5% copper.

Silver alloys are popular due to their enhanced strength and tarnish resistance. Increased hardness allows sterling silver to hold its shape better and resist scratches, making it ideal for jewelry, cutlery, and musical instruments.

• Tarnish resistance: Although not completely tarnish-free, sterling silver is more resistant compared to regular silver, allowing it to maintain its luster longer.
• Cost effectiveness: By mixing silver with less expensive metals, the overall cost is reduced, making high-quality, attractive items more accessible.

Silver alloys combine beauty with practicality, allowing for a range of applications where both aesthetics and durability are desired.

Physical properties of metals

Metals are known for certain physical traits that make them indispensable in various industries. However, the usefulness of a metal can be enhanced by alloying it with others. Let's examine some key traits of metals and how alloying changes them.

• Strength and hardness: Pure metals like gold and silver are soft, which limits their practical uses. Alloying significantly boosts these properties, making metals useful in creating durable products.


• Ductility and malleability: These characteristics allow metals to be shaped without breaking. While valuable, they can also mean a metal doesn't have enough structural strength in its pure form.


• Corrosion resistance: Alloying can improve a metal's ability to withstand corrosion, which is why stainless steel (an alloy of iron) is used in cutlery and appliances.


• Electrical and thermal conductivity: Metals like copper are great conductors. When alloyed, they often retain much of their conductivity, thus still being useful in wires and electronics.

Alloying is an essential technique that enhances the natural properties of metals, making them more suitable for practical tasks and extending their range of applications across different fields.