First of all, this experiment can't be dipped in water. If immersed in water, a reversible reaction will occur, reducing the yield. Secondly, in the process of doing the experiment, the filter paper will fall off and the glass rod will stick because it is filtered by the glass sintering funnel.
In the final weighing process, a part of filter paper was lost because of the replacement of filter paper. What's more, you accidentally spilled some, and the cumulative yield is low, with a yield of only 50%.
Extended data:
Acetylsalicylic acid is easily hydrolyzed into salicylic acid in sodium hydroxide medium. The higher the temperature, the faster the hydrolysis. The longer the reaction solution is left, the greater the degree of hydrolysis.
The neutralization reaction of aspirin should be carried out as soon as possible at low temperature. When copper aspirin is formed, the reaction time is too short, the conversion rate is not good, the yield is low, and the impurity content is high, so the stirring time should be appropriately long when copper aspirin is formed.
Baidu encyclopedia-aspirin