posted by Patrick .
Co-precipitation is the process by which undesirable materials are "carried down" and trapped on the suface or within the desired precitate. The precipitate is washed with distilled water to remove the co-precipitates which are more soluble that the precipitate. Care must be taken not to over-wash as some of the desired precipitate may be removed as well. Indicate, along with a brief explanation, whether the experimentally determined mass of analyte would be too high or too low if co-precipitation occurred, but the sample was not washed.