Final answer:
In the synthesis of acetylsalicylic acid, the role of deionized water is to decompose excess acetic anhydride, ensuring the purity of the final product by preventing contamination.
Step-by-step explanation:
The role of deionized (DI) water in the reaction to form acetylsalicylic acid is to decompose excess acetic anhydride.
Acetic anhydride is the reagent that reacts with salicylic acid to produce acetylsalicylic acid (aspirin), but if any acetic anhydride remains unreacted in the reaction mixture, it can be hydrolyzed by water to form acetic acid and will not contaminate the final product.
Deionized water is important here because it is free from ions that could otherwise interfere with the reaction or the purity of the product.
During the synthesis of acetylsalicylic acid, any residual acetic anhydride needs to be removed to ensure the purity of the product.
The use of DI water achieves this because excess acetic anhydride reacts with water to produce acetic acid and will not contaminate the final aspirin product.
This step is crucial to ensure that the final product will have the required medicinal properties without impurities that might arise from excess acetic anhydride.