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Question Video: Identifying Which Properties Are Decreased by Alloying Chemistry • 7th Grade

Alloys of a particular metal display lower malleability. Which of the following properties is also likely to be lower in these alloys? [A] Density [B] Ductility [C] Hardness [D] Melting point [E] Strength

02:50

Video Transcript

Alloys of a particular metal display lower malleability. Which of the following properties is also likely to be lower in these alloys? (A) Density, (B) ductility, (C) hardness, (D) melting point, (E) strength.

An alloy is a metallic solid solution that contains at least two different types of elements. Alloys of a metal tend to have different properties than a pure metal does. In this case, the alloy has a lower malleability than the pure metal.

Malleability is the ability of a material to be hammered or pressed into different shapes or thin sheets. This occurs because the addition of an alloying element disrupts the regular lattice that we see in a pure metal. So, it’s much harder for atoms in an alloy to slide past each other. Let’s look through our answer choices to see which property is also likely to be lower in the alloy.

The density of an alloy will be different than that of a pure metal, depending on the alloying element used. However, alloys with both a higher and lower density can have lower malleability. So, we wouldn’t know if the density is lower in the alloy described by this question. So, we can eliminate answer choice (A).

Ductility describes the ability of a material to be drawn into wires. Alloying affects ductility for the same reason we saw with malleability. The presence of the alloying element disrupts the metal lattice, making it harder to draw the metal into wires. So, we would expect an alloy with lower malleability to have lower ductility. So, (B) must be the correct answer, but let’s take a look at the other answer choices so we make sure we understand the material.

If a material has low malleability, it will be difficult to hammer it into different shapes. So, we would expect the material to be quite hard and strong. In other words, we expect the hardness and strength of the alloy to be higher, not lower. So, answer choices (C) and (E) aren’t correct.

The melting point is affected by alloying, but it doesn’t increase or decrease consistently. For example, pure copper metal has a melting point of 1085 degrees Celsius. If we look at the melting points of some copper alloys, brass and cupronickel, we can see that brass has a lower melting point than copper, but cupronickel has a higher melting point than copper. Both brass and cupronickel would have lower malleability than copper. So, we can’t expect the melting point to be lower just because the malleability is lower.

So, the only property we would expect to be lower for alloys of a metal that display lower malleability is ductility. Answer choice (B) is the correct answer.

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