Video Transcript
Which of the following period four
metals is commonly used in alloys with iron as a decorative plating on car headlamps
and has compounds that are used in the tanning of leather? (A) Scandium, (B) cobalt, (C)
copper, (D) zinc, (E) chromium.
In this question, we want to
identify which metal found in period four on the periodic table is part of an alloy
with iron used in decorative plating and is part of a compound used to tan
leather. Firstly, an alloy is a metallic
solid solution that contains at least two different types of elements. Let’s consider the applications of
the alloys and compounds containing the elements in the answer choices one at a
time.
To begin, the most common alloy of
scandium is made with aluminum and is used to make aircraft. A common use of scandium compounds
is in mercury vapor lamps to make the light look more natural. These are only some of the uses of
scandium alloys and compounds. But we know that scandium is very
rare and is not involved in tanning leather or decorative plating, so we can
eliminate it from the list.
Cobalt alloys are used in
computers, MRI machines, and in some types of car batteries. Cobalt compounds are often used as
coloring agents for glass or enamel. These common uses of cobalt alloys
and compounds do not match those listed in the question, so we can eliminate cobalt
from our list.
The next element we will discuss is
copper. One of the most important alloys of
copper is bronze, which contains copper and tin. Copper compounds have a variety of
important uses, including insecticides and fungicides, but none are used to tan
leather. Therefore, we can also eliminate
copper from our list.
The element zinc can form a
well-known alloy with copper known as brass, which is very malleable and used to
make instruments and decorative ornaments. Common uses of zinc compounds
include sunscreens and illuminating paints. However, these compounds are not
used to tan leather, so we can also eliminate zinc from our list.
Finally, we can discuss
chromium. Chromium forms an alloy with iron
called ferrochrome, which is corrosion resistant and is used for the decorative
plating of car headlamps. In addition, chromium salts are
used in the tanning of leather. Chromium helps to form cross-links
between collagen fibers in the animal hide.
In conclusion, the period four
metal that is commonly alloyed with iron for decorative plating of car headlamps and
has compounds involved in tanning leather is chromium, or answer choice (E).
