Problem 36 - Chemistry The Science in Context

Question

White gold was originally developed to give the appearance of platinum. One formulation of white gold contains \(25 \%\) nickel and \(75 \%\) gold. Which is more malleable, white gold or pure gold? Explain your answer.

Step-by-Step Solution

Answer

Answer: Pure gold is more malleable than white gold. This is because pure gold is a very soft and highly malleable material, whereas white gold is an alloy containing gold and harder metals such as nickel, which reduces its overall malleability.

Step 1: Definition of Malleability

Malleability is a property of a material that allows it to be hammered or rolled into thin sheets without breaking. Generally, the more malleable a material, the easier it is to shape it.

Step 2: Pure Gold

Pure gold is a very soft and highly malleable material. It can be easily shaped and is often used in the creation of various types of jewelry and artifacts.

Step 3: White Gold

White gold is an alloy that contains gold and other metals, such as nickel. The given formulation of white gold contains \(25 \%\) nickel and \(75 \%\) gold.

Step 4: Effect of Nickel on Malleability

Nickel is a harder metal compared to gold, which means it has a lower malleability. When nickel is added to gold to create an alloy like white gold, it increases the overall hardness of the mixture and reduces its malleability.

Step 5: Comparison of Malleability

Comparing the malleability of pure gold and white gold, we can conclude that pure gold is more malleable than white gold. The addition of nickel to gold in the creation of white gold decreases its overall malleability due to the harder nature of nickel.

Key Concepts

White Gold

White gold is a popular alloy in the jewelry industry.
It's loved for resembling platinum but usually at a lower cost.
White gold typically contains gold mixed with other white metals.

• Composition: This exercise shows a common mix of white gold, consisting of 25% nickel and 75% gold.
• Use in Jewelry: White gold offers a sleek, shiny look, often used for wedding bands and other jewelry items.
• Characteristics: Because of the added nickel, white gold is harder than pure gold.

This increased hardness provides durability but results in lower malleability compared to its pure form.

Pure Gold

Pure gold, often referred to as 24-karat gold, is gold in its purest form.
It is highly prized for its distinctive yellow hue and exceptional malleability.

• Appearance: Pure gold has a characteristic warm yellow color.
• Malleability: It can be easily hammered into thin sheets or drawn into wires without breaking.
• Use in Crafting: Due to its softness, jewelers usually mix it with harder metals for increased durability.

Pure gold’s high malleability allows it to be fashioned into intricate shapes, making it ideal for elaborate jewelry designs.

Metal Alloys

Metal alloys are mixtures of two or more elements, where at least one is a metal.
Alloys are engineered to enhance particular properties lacking in the pure metals.

• Composition: A well-known example is white gold, an alloy of gold and nickel that alters the properties of gold.
• Properties: Alloys can be designed to improve strength, corrosion resistance, or even color.
• Advantages: Using alloys allows for a wider range of applications beyond what pure metals can provide.

The process of alloying usually results in a compromise; adding stronger metals reduces malleability but increases other desirable traits like toughness.