Oxidation Reduction

To determine the oxidation states of each element in calcium oxychloride, CaOCl₂, follow these systematic steps:

Understand the Compound's Neutrality:

The compound CaOCl₂ is neutral overall. This means that the sum of the oxidation states of all atoms in the molecule must equal zero.

Assign Known Oxidation States:

Calcium (Ca): Calcium is an alkaline earth metal and typically exhibits an oxidation state of +2 in its compounds.

Oxidation state of Ca = +2

Oxygen (O): Oxygen usually has an oxidation state of -2 in most of its compounds, except in peroxides or when bonded to fluorine.

Oxidation state of O = -2

Chlorine (Cl): Chlorine can exhibit multiple oxidation states, commonly -1 in its compounds. However, in compounds with metals and oxygen, it can also show positive oxidation states.

Set Up the Equation for Oxidation States:

Let the oxidation state of chlorine be x. Since there are two chlorine atoms in CaOCl₂, their combined contribution will be 2x.

Sum of oxidation states = 0

(+2) + (-2) + 2x = 0

Solve for the Oxidation State of Chlorine:

+2 - 2 + 2x = 0

0 + 2x = 0

2x = 0

x = 0

Interpretation:

The calculation suggests that each chlorine atom has an oxidation state of 0. However, this contradicts the typical behavior of chlorine, which usually has a negative oxidation state. Therefore, it's essential to reassess the assumption.

Re-evaluate Chlorine's Oxidation State:

Since the above result is unphysical, it's more plausible that chlorine exists in multiple oxidation states within the same compound to balance the overall charge.

Assumption:

Let one chlorine atom have an oxidation state of +1 and the other have -1. This accounts for the neutrality of the compound.

Oxidation state of Ca = +2 Oxidation state of O = -2 Oxidation states of Cl = +1 and -1

Verify the Charge Balance:

(+2) + (-2) + (+1) + (-1) = 0

0 = 0

The charges balance, confirming the oxidation states.

Final Assignment of Oxidation States:

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