Video Transcript
The following picture shows a
potassium compound dissolving in water. This compound is commonly used in
laboratories to oxidize other chemicals. Which of the following period four
metals does it also contain atoms of? (A) Chromium, (B) nickel, (C)
scandium, (D) manganese, (E) zinc.
In this question, we want to find
out which period four metal is part of the compound that is shown dissolving in
water. Answer choices (A) through (D) are
transition metals, and transition metal ions are known for their variety of
colors. For example, in aqueous solution,
the chromium three plus ion has a dark green color, while the nickel two plus ion is
pale green. The scandium three plus ion is
colorless, and the manganese two plus ion is pale pink.
While none of these ions have the
deep purple color we can see in the center of the picture, manganese is worth
investigating further. Due to its large number of
oxidation states, manganese can form a wide variety of ions. Some of these ions are polyatomic
ions that contain oxygen, known as oxyanions. The color of these ions in solution
varies widely. However, we notice that the MnO4−
ion produces a violet color in solution. The name of this ion is the
permanganate ion.
We are told that the picture shows
a potassium compound in water. Therefore, the compound must be
potassium permanganate, or KMnO4. Potassium permanganate is a
well-known oxidizing agent, which means that it can be used to oxidize other
chemicals. Because of its oxidizing
properties, potassium permanganate is used as a disinfectant, as a fungicide, and in
water treatment.
In conclusion, the potassium
compound shown dissolving in water is potassium permanganate, which is composed of
potassium, manganese, and oxygen atoms. Therefore, the period four metal
that the compound contains is manganese, or answer choice (D).
