Step 4 Filtration with Fluted Filter (Removal of Impurities)
You will use gravity filtration through a fluted filter paper to collect the unwanted solid impurities, including the charcoal. A piece of very porous filter paper is fluted by folding it in half, then in quarters, eighths, etc. The fluted filter paper is then unfolded and placed into a stemless conical funnel. The funnel is stemless so that the solid does not crystallize in the stem during filtration. Your instructor will demonstrate how to flute a filter paper. The filter paper must be porous; otherwise, the solid crystallizes in the filter paper. Be sure to use the correct filter paper for this step. The fluted filter paper provides more surface area for the solution, making it more efficient than an unfluted filter paper. It is important for this step to be efficient to keep any solid from crystallizing in the filter paper. You will collect the filtrate in an Erlenmeyer flask.