Oxidation State of Nitrogen in (NH4)2Cr2O7

The compound (NH4)2Cr2O7 is known as ammonium dichromate. To determine the oxidation state of nitrogen in this compound, we need to consider the known oxidation states of other elements and apply certain rules.

Rules for determining the oxidation state:

1. The oxidation state of an atom in an element is zero.
2. The sum of oxidation states of all atoms in a neutral compound is zero.
3. In an ion, the sum of oxidation states of all atoms is equal to the charge of the ion.
4. Oxygen has an oxidation state of -2, except in peroxides where it is -1.
5. Hydrogen has an oxidation state of +1, except in metal hydrides where it is -1.
6. The sum of oxidation states of all atoms in a polyatomic ion is equal to the charge of the ion.

Analysis of (NH4)2Cr2O7:

The compound (NH4)2Cr2O7 consists of ammonium ions (NH4+) and dichromate ions (Cr2O7^2-).

1. Ammonium ion (NH4+):
- Hydrogen always has an oxidation state of +1.
- Since the overall charge of the ammonium ion is +1, the nitrogen must have an oxidation state of -3 to balance the charge. (NH4+) = +1, and (+1) + 4(-1) = +1.

2. Dichromate ion (Cr2O7^2-):
- Oxygen always has an oxidation state of -2.
- Since the overall charge of the dichromate ion is -2, the sum of the oxidation states of chromium and oxygen must equal -2.
- Let the oxidation state of chromium be x. Therefore, 2(x) + 7(-2) = -2.
- Solving the equation, we find that the oxidation state of chromium is +6.

Oxidation state of Nitrogen:

Since the nitrogen ion (NH4+) has an oxidation state of -3 and there are two nitrogen atoms in the compound, the total oxidation state of nitrogen is -6.

In order to balance the oxidation states of all the atoms in the compound and meet the rule that the sum of oxidation states in a neutral compound is zero, the oxidation state of nitrogen in (NH4)2Cr2O7 is +6.

Summary:

The oxidation state of nitrogen in (NH4)2Cr2O7, which is ammonium dichromate, is +6. This is determined by considering the known oxidation states of other elements in the compound and applying the rules for determining oxidation states. The nitrogen in the ammonium ion (NH4+) has an oxidation state of -3, and since there are two nitrogen atoms in the compound, the total oxidation state of nitrogen is -6. To balance the oxidation states of all the atoms in the compound and meet the rule that the sum of oxidation states in a neutral compound is zero, the oxidation state of nitrogen is +6.