All that Glitters Above_02

When two or more metals are mixed, it is called an alloy. Steel is an alloy. You may have heard of aluminum alloy. It is a mixture of aluminum and silicon. Aluminum alloy is found in many things you buy. Your bicycle or your baseball bat may be made from it. These are just a few examples of alloys.

Not all mixtures are alloys. Alloy is a term that refers only to mixtures of metal. What does this have to do with gold? As it turns out, a whole lot. When you buy gold, you are most likely buying gold alloy.

So how can you buy gold jewelry and not get ripped off?

He reminds us that a gold color does not tell us much. We can buy gold color in paint form and apply it to a brick. In the case of gold, it is common for it to be a mixture. Gold is a very soft metal. By mixing it with other metals, it becomes more durable or strong. This also helps to keep the cost down.

In the US, there is a system in place to inform the buyer. The karat amount tells you the fraction of gold in the item. For example, 24 karats is pure gold. It’s also costs much more because it is not an alloy. 12-karat gold is 12  parts of the possible 24. That means the metal you are buying is 50 percent gold. It is much less expensive than 24-karat gold because it is mixed with other metals. 18-karat gold is 18 parts gold of the possible 24 or 75 percent gold. The cost of 18-karat gold is somewhere in the middle because, like 12-karat gold, it is also an alloy. 18-karat gold has more pure gold and fewer other metals mixed into it.

“But what if someone is lying to us? How do we know if it is 12- or 18-karat gold in the store?” you ask. “So how could we find out given what we know?” Mr. Jones asks, once again peeking over the top of his glasses.

“Uh! We do an investigation!” John shouts, barely able to contain himself. He is always ready for this part of the class.

“Of course,” Mr. Jones responds as he pushes his glasses back up on his nose. “Let’s learn about some ways we can tell what an object is made of by using the properties of matter. Back to the lab area, everyone,” he chants.