Final answer:
The balanced chemical equation for the reaction between salicylic acid and acetic anhydride, catalyzed by an acid, to form aspirin (acetylsalicylic acid) and acetic acid is depicted in the detailed answer.
Step-by-step explanation:
The balanced equation for the reaction between salicylic acid and acetic anhydride in the synthesis of aspirin is:
C7H6O3 (salicylic acid) + C4H6O3 (acetic anhydride) → C9H8O4 (aspirin) + C2H4O2 (acetic acid)
This reaction is typically catalyzed by an acid such as sulfuric acid (H2SO4) or phosphoric acid (H3PO4). The process is an example of an esterification reaction, where the hydroxyl group (-OH) of the salicylic acid reacts with the acetic anhydride to form acetylsalicylic acid (aspirin) and acetic acid as a byproduct.