【Daily Question】Chemical Analysis Version 2021.3.26

I got it wrong; I thought that weight analysis would require a certain particle size for the precipitate, so as to avoid leakage during the filtration process. It was a bit of an assumption on my part. Friends who have not yet replied can find the correct answer in the following description: Requirements for precipitates in gravimetric analysis. 1. Requirements regarding the form of the precipitate: (1) The precipitate should have low solubility, so as to ensure sufficient completeness of the precipitation reaction. If the precipitation is incomplete, it will cause analytical errors. (2) The precipitate should be pure; efforts should be made to avoid contamination by impurities, so as to prevent measurement errors. Additionally, the precipitate should be easy to filter and wash. To obtain a pure and easily filterable precipitate. It is necessary to select appropriate precipitation conditions based on the different characteristics of crystalline and amorphous precipitates. (3) The precipitate should be easily converted into a form suitable for weighing. 2. Requirements for the symmetric mass form: (1) The actual composition of the mass form must exactly correspond to the chemical formula; this is the most fundamental requirement for a symmetric mass form. If the composition does not match the chemical formula, it is impossible to obtain correct analysis results. (2) The weighing form must be stable. Stability refers to the fact that the weighed form does not easily absorb moisture and carbon dioxide from the air, and does not decompose easily when dried or burned. If the weighing form is unstable, accurate weighing is not possible. (3) The relative molecular mass of the weighed form should be relatively large. The larger the relative molecular mass of the weighing form, the smaller the relative content of the component being measured in it; this helps to reduce the relative errors during weighing and improves the accuracy of the analysis.