The optimal ratio of salicylic acid and acetic anhydride needed to produce a maximum yield of aspirin in a chemical synthesis reaction is 1:1, based on their stoichiometry. This is because one molecule of salicylic acid reacts with one molecule of acetic anhydride to produce one molecule of aspirin acetylsalicylic acid and one molecule of acetic acid.The temperature and reaction time can significantly affect the yield of aspirin in this synthesis reaction. Generally, increasing the temperature speeds up the reaction rate, leading to a faster formation of aspirin. However, if the temperature is too high, it may cause the decomposition of aspirin, reducing the overall yield. A common temperature for this reaction is around 85C.The reaction time also plays a crucial role in determining the yield of aspirin. A longer reaction time allows for more complete conversion of the reactants to the product, thus increasing the yield. However, if the reaction is allowed to proceed for too long, side reactions or decomposition may occur, leading to a decrease in yield. Typically, a reaction time of 15-30 minutes is used for this synthesis.To optimize the yield of aspirin, it is essential to carefully control the ratio of reactants, temperature, and reaction time. Additionally, using a catalyst such as concentrated sulfuric acid or phosphoric acid can help increase the reaction rate and improve the overall yield.