Which color is typically produced by cobalt(II) oxide in compounds or glass?

• A. Blue-violet
• B. Green
• C. Red
• D. Yellow

Answer: (A)

Verified step by step guidance

1. Understand that the color produced by a transition metal compound, such as cobalt(II) oxide, is due to the d-d electronic transitions within the metal ion when it is in a specific chemical environment.
2. Recall that cobalt(II) ions (Co²⁺) typically produce characteristic colors when incorporated into compounds or glass because of their electronic structure and the way they absorb and transmit visible light.
3. Recognize that cobalt(II) oxide, when used as a coloring agent in glass or ceramics, imparts a distinctive blue to blue-violet color due to the specific wavelengths of light absorbed and transmitted by the Co²⁺ ions.
4. Compare this with other common transition metal oxides: for example, chromium compounds often produce green colors, iron oxides can produce red or yellow colors, but cobalt(II) oxide is well-known for its blue-violet coloration.
5. Conclude that the typical color produced by cobalt(II) oxide in compounds or glass is blue-violet.