Final answer:
The percent Pb reported in the analysis would be overestimated if the PbCrO4 precipitate retained water, whereas it would be underestimated if some of the lead salt was spilled or if the orange PbCrO4 precipitate was not fully transferred to the filter paper.
Step-by-step explanation:
When analyzing the effect on the reported percentage of Pb in an analysis, we must consider the following:
- Not completely dried precipitate: If the precipitate of PbCrO4 was not completely dried, it would retain some water weight. This would result in a higher recorded mass of the precipitate, causing an overestimation of the percent Pb in the sample since the additional weight is not actually lead chromate.
- Spilled unknown lead salt: If some of the unknown lead salt was spilled while being transferred to the beaker, the total amount of lead present in the sample would be less than anticipated. This would lead to an underestimation of the percent Pb because the amount of precipitate formed would be less than expected for the original mass.
- Incomplete transfer of precipitate: If the bright orange precipitate of PbCrO4 was not completely transferred to the filter paper, the mass of lead in the precipitate collected would be less than the true amount present in the sample. This also results in an underestimation of the percent Pb because the analysis would indicate less lead than what is actually there.