Another potential source of error that could lead to lost mass of the precipitate is incomplete filtration. If the filter paper is not properly placed in the funnel or if the funnel is not properly supported, some of the precipitate may pass through the filter paper and be lost. This could happen if the filter paper tears or if it is not the correct size for the funnel. Additionally, if the filter paper becomes clogged with precipitate, it may no longer be able to effectively separate the solution from the solid, leading to incomplete filtration and lost mass of the precipitate.