What is Filtration?
Filtration: A separation technique used to separate an insoluble solid from a liquid (or solution) by passing the mixture through a porous material that traps the solid particles.
Filtration works because of particle size. The filter material (usually filter paper) has tiny holes , large enough for liquid molecules to pass through, but small enough to trap solid particles.
You have probably seen filtration in everyday life without realising it:
- A coffee maker filtering coffee grounds from liquid coffee
- A swimming pool filtration system removing debris from water
- A sieve separating pasta from boiling water
Think of filter paper like a net. A fishing net lets water flow straight through, but traps the fish. Filter paper does the same , it lets the liquid "escape" while holding onto the solid particles.
Key Vocabulary
Before diving deeper, make sure you know these essential terms:
Filtrate: The liquid that passes through the filter paper and is collected in the container below (e.g., a beaker or conical flask).
Residue: The solid that is trapped by the filter paper and remains behind after filtration.
Mixture: A combination of two or more substances that are not chemically combined and can be separated by physical means.
Insoluble: A substance that does not dissolve in a given liquid. For example, sand is insoluble in water.
Soluble: A substance that does dissolve in a given liquid. For example, salt is soluble in water.
A useful memory trick: filtRATe , think of a rat running through a hole and escaping. The filtrate is what escapes through the filter. The residue is what is left behind (like a residue of leftovers).
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