To determine the oxidation states of each element in calcium oxychloride (CaOCl2), follow these steps:
Compound Neutrality:
CaOCl2 is a neutral compound. The sum of the oxidation states of all its atoms must equal zero.
Assign Known Oxidation States:
Calcium (Ca): As an alkaline earth metal, calcium typically has an oxidation state of +2.
Oxidation state of Ca: +2
Oxygen (O): Oxygen usually has an oxidation state of -2, except in peroxides or when bonded to fluorine.
Oxidation state of O: -2
Chlorine (Cl): Chlorine can have multiple oxidation states, commonly -1. In compounds with metals and oxygen, it can also be positive.
Set Up the Equation:
Let x be the oxidation state of chlorine. With two chlorine atoms, their total contribution is 2x.
Sum of oxidation states = 0
(+2) + (-2) + 2x = 0
Solve for Chlorine's Oxidation State:
+2 - 2 + 2x = 0
0 + 2x = 0
2x = 0
x = 0
Initial Interpretation (and its Flaw):
This calculation suggests a chlorine oxidation state of 0, which is unusual. This implies a need to reassess our assumptions.
Re-evaluating Chlorine's Oxidation State:
Given the unphysical result above, it's more likely that chlorine exists in multiple oxidation states within the compound to achieve charge balance.
Assumption:
Assume one chlorine atom has an oxidation state of +1 and the other -1, maintaining compound neutrality.
Oxidation state of Ca = +2 Oxidation state of O = -2 Oxidation states of Cl = +1 and -1
Verify Charge Balance:
(+2) + (-2) + (+1) + (-1) = 0
0 = 0
The charges balance, validating the proposed oxidation states.
Final Oxidation State Assignments:
Calcium (Ca): +2 Oxygen (O): -2 Chlorine (Cl): +1 and -1
Therefore, the oxidation states in CaOCl2 are:
(2) Calcium +2, Oxygen -2, Chlorine +1 and -1