Problem: In each of the following situations, what type of filtration device would you use?

A. Remove powdered decolorizing charcoal from 20mL of solution?

B. Collect crystals obtained from crystallizing a substance from about 1 mL of solution.

C. Remove a very small amount of dirt from 1 mL of liquid?

D. Isolate 2.0 g of crystals from about 50 mL of solution after performing a crystallization?

E. Remove dissolved colored impurities from about 3 mL of solution?

F. Remove solid impurities from 5 mL of liquid at room temperature?

A. Filtration by gravity

B. Syringe filter

C. Syringe filter

D. Filtration by gravity

E. Syringe filter

F. Filtration by gravity / Vacuum filtration.

Explanation:

Filtration is a mixture of separation techniques to separate solids from liquids. The filtration can be done by gravity, by pressure or by vacuum. The correct filtration is chosen by the characteristics of the mixture.

A. The particles are big, so it's possible to use a funnel and a filter paper with the right numeration (the diameter of the pores must be smaller than the particles). The filtration will happen by gravitation.

B. Because the volume is too small (1 mL), it can be used as a syringe filter, a small device in which the solution is put in the syringe, and then, by pressure, the solution goes from the filter. Thus, the filtration is done by pressure.

C. As letter B, the small volume indicates a pressure filtration by a syringe filter.

D. In this case, such as letter A, it's possible to use gravitation filtration.

E. Because of the volume is too small, such as letters B and C, the pressure filtration by a syringe filter is more indicate.

F. In this case, the filtration can be done by gravitation, and a vacuum can be added to accelerate it because is a small volume with solid impurities.