posted by Sheryl on .
Question: While performing a crystallization, you obtain a light tan solution after dissolving your crude product in hot solvent. A decolorizing step is determined to be unnecessary, and there are no solid impurities present. Should you perform a filtration to remove impurites before allowing the solution to cool? Why or why not?
My answer: Since decolorization is not deemed necessary, we can assume that the tan color is due to the desired product and does not need to be removed. There are no solid impurities and if we did a filtration, we could lose some product due to cooling. Therefore, filtering is unnecessary.
sounds good to me. You could also introduce impurities (unintended, of course) from the filtration. In some of the work I did we had to make a correction for the trace metals found in filter paper. Ashing the paper simply added the extra trace metals (mostly copper) to the crucible. So we ran blank pieces of filter paper through the procedure, too, and used the average from three to subtract as a blank.