Why is nitrous acid oxidant as well as reductant?

Explanation

To understand why nitrous acid (HNO2) can act as both an oxidant and a reductant, we need to analyze its chemical properties and oxidation states. Here’s a step-by-step breakdown:

### Step 1: Identify the Structure and Oxidation State of Nitrous Acid
- The chemical formula for nitrous acid is HNO2.
- In HNO2, nitrogen (N) is bonded to one hydrogen (H) and two oxygen (O) atoms. One of the oxygen atoms is typically involved in a double bond with nitrogen.
- To find the oxidation state of nitrogen in HNO2, we can use the following formula:
\[
\text{Oxidation state of N} + \text{(Oxidation state of H)} + 2 \times \text{(Oxidation state of O)} = 0
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