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?

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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