Filtration - Key Points

What is the purpose of filtration?

• To mix two liquids

• To separate an insoluble solid from a pure liquid or a solution

• To dissolve a solid in a liquid

• To evaporate a liquid

What does filtration usually involve?

• A circle of filter paper folded to make a cone and placed into a filter funnel

• A metal sieve

• A plastic bag

• A glass rod

Fill in the blank: The ______ is the liquid which passes through the filter paper.

• filtrate

• residue

• precipitate

• solvent

A sieve can be used to separate small stones from fine sand. Why does sand pass through a sieve but stones do not?

• Because sand particles are smaller than the holes in the sieve, while stones are larger.

• Because stones are lighter than sand.

• Because sand is heavier than stones.

• Because stones dissolve in water.

The water molecules passed through the tiny holes in the filter paper, but the sand particles did not because:

• water molecules are smaller than sand particles

• sand particles are soluble in water

• filter paper is designed to block water molecules

• sand particles can pass through any filter

What is the residue in the filtration process?

• The liquid that passes through the filter paper

• The solid that remains on the filter paper

• The filter paper itself

• The mixture before filtration

What is the purpose of the filter paper in the filtration process?

In the filtration process, what happens to the particles of the liquid including any dissolved solutes?

• They pass through the filter

• They are trapped by the filter

• They evaporate

• They react with the filter

Why can't larger particles pass through the filter paper in the filtration process?

• Because they are too large to pass through the pores of the filter paper.

• Because they dissolve in the filter paper.

• Because they react with the filter paper.

• Because they evaporate before passing through.

Why can't filtration be used to separate salt from sea water?

• Because salt is dissolved in water

• Because salt is heavier than water

• Because salt is lighter than water

• Because salt is a solid