1. Assign known oxidation states:
* Calcium (Ca): +2 (Group 2 element)
* Oxygen (O): -2 (except in peroxides)
2. Set up an equation:
Let the oxidation state of carbon be "x". Since there are two carbon atoms in the formula, we'll use 2x.
The sum of the oxidation states in a neutral compound must equal zero:
+2 + 2x + 4(-2) = 0
3. Solve for x:
* +2 + 2x - 8 = 0
* 2x = 6
* x = +3
Therefore, the oxidation state of carbon in CaC₂O₄ is +3.
