Alloys - Explained

Chem Academy

4 Sept 201505:48

Summary

TLDRIn this educational video, Mr. Millington explores the concept of alloys, defined as homogeneous mixtures of metals designed to enhance strength or reduce cost while maintaining key properties. Examples include steel (98% iron, 2% carbon), brass (copper and zinc), and bronze (copper and tin). The video also explains the carat system used in jewelry to denote gold purity, with common alloys like 8k (33% gold), 14k (58% gold), and 18k (75% gold) contrasted with 24k pure gold. This insight into alloys' role in everyday objects and jewelry is both informative and engaging.

Takeaways

🔍 Alloys are homogeneous mixtures of metals, designed to enhance strength or reduce cost while maintaining key properties.
🏗 Steel is an alloy primarily composed of iron and carbon, used extensively in construction for its strength.
🎺 Brass is an alloy made from copper and zinc, commonly used in musical instruments and plumbing fixtures.
🗿 Bronze is an alloy consisting of copper and tin, historically significant and used for coins, weapons, and sculptures.
💍 Gold jewelry often contains alloys to increase durability; pure gold is too soft for practical use.
📊 The carat system measures the purity of gold in jewelry, with 24 karat gold being 100% pure gold.
🔢 Eight carat gold is 33% gold, while 14 karat gold is 58% gold, and 18 karat gold is 75% gold, with the remainder being other metals.
🏵 Gold alloys are mixed with metals like copper, nickel, and silver to improve hardness and wear resistance.
💎 The value of gold coins is significantly higher than their face value due to the high purity of gold they contain.
🌐 Alloys are crucial in various industries for their ability to combine the best properties of different metals into a single material.

Q & A

What is an alloy?
-An alloy is a homogeneous mixture or solution of two or more metals that are mixed together evenly to enhance properties like strength or to reduce costs.
Why are alloys made?
-Alloys are made to add strength to metals or reduce the cost of materials while preserving important properties of the metals.
What is steel made of?
-Steel is an alloy made of 98% iron and 2% carbon, which gives it extra strength.
What metals make up brass?
-Brass is an alloy made up of varying amounts of copper and zinc.
What is bronze composed of?
-Bronze is an alloy composed of 88% copper and 12% tin.
How is gold used in jewelry classified in terms of alloys?
-Most gold used in jewelry is an alloy, usually mixed with metals like silver, nickel, or copper to make it more durable, as pure gold is soft and malleable.
What does the carat system measure in gold jewelry?
-The carat system measures the amount of pure gold present in the jewelry. For example, 8-karat gold is 33% gold, while 24-karat gold is 100% gold.
What is the composition of 14-karat gold?
-14-karat gold is composed of 58% gold and 42% other metals or alloys.
Why is pure gold not commonly used for everyday jewelry?
-Pure gold, such as 24-karat gold, is soft and malleable, making it prone to scratches and dents, which is why it is mixed with other metals for durability.
What is the difference between 18-karat and 24-karat gold?
-18-karat gold contains 75% gold and 25% other metals, whereas 24-karat gold is pure gold (100%) and is not an alloy.