The chemical equation for acetic acid (also known as ethanoic acid) is represented by its molecular formula, which is \( \text{C}_2\text{H}_4\text{O}_2 \) or sometimes \( \text{CH}_3\text{COOH} \). In its simplest form, acetic acid can be described as:
\[ \text{C}_2\text{H}_4\text{O}_2 \]
If you need a reaction involving acetic acid, please specify, and I can provide that as well!