The empirical formula of chromium oxide depends on the specific compound you're referring to. There are two common chromium oxides:

* Chromium(III) oxide: This is the more common oxide, and its formula is Cr₂O₃.

* Chromium(VI) oxide: This oxide is highly toxic and corrosive, and its formula is CrO₃.

How to determine the empirical formula:

1. Identify the elements: Chromium (Cr) and Oxygen (O)

2. Determine the oxidation state of chromium: This will tell you the ratio of chromium to oxygen atoms.

* In chromium(III) oxide, chromium has an oxidation state of +3.

* In chromium(VI) oxide, chromium has an oxidation state of +6.

3. Find the simplest whole-number ratio of chromium to oxygen:

* Cr₂O₃: The ratio is 2:3

* CrO₃: The ratio is 1:3

Therefore, the empirical formulas are:

* Chromium(III) oxide: Cr₂O₃

* Chromium(VI) oxide: CrO₃