Thursday
May 5, 2016

# Homework Help: Filtration

Posted by Sheryl on Saturday, September 30, 2006 at 9:25pm.

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

A. Remove powdered decolorizing charcoal from 20mL of solution?
My answer: Filter Aid or Celite (diatomaceous earth)

B. Collect crystals obtained from crystallizing a substance from about 1 mL of solution.
Filter-tip pipette or Craig tube

C. Remove a very small amount of dirt from 1 mL of liquid?
Filter-tip pipette

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

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

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

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

A. Remove powdered decolorizing charcoal from 20mL of solution?
My answer: Filter Aid or Celite (diatomaceous earth)

Your answer may be perfectly ok but I always worry about contaiminating the material with the "other" solid; i.e., in this case whatever filter aid you are using (mascerated paper et al and celite). Would just plain filter paper work as well?

B. Collect crystals obtained from crystallizing a substance from about 1 mL of solution.
Filter-tip pipette or Craig tube

I have had no experience with a filter tip pipette or a Craig tube but I can imaging what they are. From such a small volume you could almost decant the liquid and allow the crystals to dry.

C. Remove a very small amount of dirt from 1 mL of liquid?
Filter-tip pipette

Ok.

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

It would need to be a SMALL Buchner funnel. And 2 g of crystals can get lost on a large sheet of filter paper. Using a regular piece of filter paper and funnel would concentrate the 2 g in the center of the cone. The filter-tip pipette might work ok here too. Most of these answers are personal preferances, of course, but I would not go with a Buchner, even a small one.

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

This would probably work but you then must address the problem of getting rid of the charcoal. That becomes a repeat of one of the above questions.

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

good, but this answer doesn't imply the others are not. I was just raising questions about some of them.