The oxidation state(s) of nitrogen in ammonium nitrite is/are

Analyze the question: Ammonium nitrite is NH₄NO₂. It contains two different nitrogen atoms, one in the ammonium ion (NH₄⁺) and one in the nitrite ion (NO₂⁻). We need the oxidation state of each.

Concept: In an ion, the oxidation states of all atoms add up to the charge on the ion. Hydrogen is usually +1 and oxygen is usually -2.

Solution:

1. Ammonium ion, NH₄⁺: • Let N = x • x + 4(+1) = +1 • x + 4 = +1 • x = -3

2. Nitrite ion, NO₂⁻: • Let N = y • y + 2(-2) = -1 • y - 4 = -1 • y = +3

So nitrogen shows two oxidation states in ammonium nitrite: -3 (in NH₄⁺) and +3 (in NO₂⁻).

Checking the options:

• A. -3, +3 ✔ matches our working
• B. +5 ✘ (this is nitrogen in nitrate, NO₃⁻)
• C. -3, +5 ✘ (this would be ammonium nitrate, NH₄NO₃)
• D. -3 ✘ (only accounts for the ammonium nitrogen)

Tip: Do not confuse nitrite with nitrate. Nitrite (NO₂⁻) has fewer oxygens, so nitrogen is +3. Nitrate (NO₃⁻) has more oxygens, so nitrogen is +5. Also, when a compound contains a polyatomic ion, split it into its ions first and work out each one separately.