What type of mixtures can be separated by filtration?

You can use filtration to separate a of a solid in a liquid or a solid in a gas.

Filtration is a separation process in which a mixture is passed through a filter that allows one component to pass through uninhibited but blocks another component from passing through.

In general this method sorts by size, with the filter acting as a barrier that allows smaller particles to go through but keeps larger particles back.

Think of a colander separating spaghetti from water or a coffee filter holding back coffee grounds while water passes through.

In order to sort these mixtures, the components must be noticeably different in size/composition. Therefore the mixture must be heterogeneous.

Another example would be an air filter which helps to remove solids like dust or pollen in HCAC systems to give better air quality inside of your home.

A laboratory example

You can produce solid calcium carbonate (chalk) by combining aqueous solutions of calcium chloride and sodium carbonate.

##"CaCl"_2"(aq) + Na"_2"CO"_3"(aq) → CaCO"_3"(s) + 2NaCl(aq)"##

The ##"CaCO"_3## forms as a precipitate.

The mixture can be poured through a funnel with a filter paper inserted.

The ##"CaCO"_3## is trapped by the paper, but the ##"NaCl"## passes through the filter paper with the water.

The video below shows how filtration can be used to separate calcium carbonate (chalk) from water. Video from: Noel Pauller