What is the IUPAC name of the compound Cro3?
Chromium trioxide
Chromium(VI)oxide
Chromium oxide
Chromium(III)oxide
Chromium(I)oxide
The correct answer and explanation is :
The correct IUPAC name for CrO₃ is Chromium(VI) oxide.
Explanation:
- Understanding the Oxidation State of Chromium
- Oxygen typically has an oxidation state of -2.
- The compound CrO₃ consists of one chromium (Cr) atom and three oxygen (O) atoms.
- To determine the oxidation state of chromium, let’s set up an equation: [
x + 3(-2) = 0
] [
x – 6 = 0
] [
x = +6
] So, the oxidation state of chromium in CrO₃ is +6.
- IUPAC Naming Rules
- The name of a binary compound typically follows the format:
[Metal name] (Oxidation state in Roman numerals) [Nonmetal name with -ide or -oxide] - Since chromium is in the +6 oxidation state, we indicate this in Roman numerals: Chromium(VI).
- Since oxygen is present as the anion, we use “oxide” to complete the name. Final IUPAC name: Chromium(VI) oxide.
- Why Other Options Are Incorrect?
- Chromium trioxide: This is a common name, not the IUPAC name.
- Chromium oxide: This name is too vague and does not specify the oxidation state.
- Chromium(III) oxide: This corresponds to Cr₂O₃, where chromium is in the +3 state.
- Chromium(I) oxide: No such stable oxide of chromium with +1 oxidation state exists.
Thus, the correct answer is Chromium(VI) oxide.