Why is it necessary to heat the collected filtrate (solid on the filter paper) prior to weighing in a gravimetric analysis experiment?

• A. To increase the solubility of the solid for easier weighing
• B. To ensure the filter paper does not react with the solid
• C. To remove any residual moisture that could affect the mass measurement
• D. To prevent the solid from decomposing during storage

Answer: (C)

Verified step by step guidance

1. Understand that in gravimetric analysis, the goal is to accurately measure the mass of a solid product obtained after filtration.
2. Recognize that any residual moisture (water or solvent) trapped in or on the solid will add extra mass, leading to an inaccurate measurement.
3. Heating the collected solid on the filter paper helps to evaporate this residual moisture, ensuring that only the dry solid is weighed.
4. This step is crucial because the presence of moisture can cause the measured mass to be higher than the true mass of the solid, affecting the accuracy of the analysis.
5. Therefore, heating prior to weighing ensures the mass corresponds solely to the solid analyte, improving the reliability of the gravimetric results.