Question

When collecting your solid, why should the filter paper in the Buchner funnel be wetted with some of the cold recrystallization solvent before a recrystallization mixture is filtered?

Answer 1

Answer: It is important to wet the filter paper in the Buchner funnel first with cold re crystallization solvent before the re crystallization mixture being filtered to minimize gaps around the edges of the filter paper which can prevent mechanical impurities from passing through. This gives better filtration where most impurities can be filtered. Furthermore, it provides good vacuum.