While many substances (sugar, salt ... ) dissolve in water, other substance do not. For more on substance that dissolve, that are soluble you should check out solutions here

1st we can decant the water from the sand.

for substance that do not dissolve and are big enough we have filtration

In some ways the following is like filtration

Sand or mud do not dissolve but because their particles are so small they said to be suspended in the solvent.

To be suspended means that while the solution is kept from being at rest the particles become mixed with the solvents particles. If the solution is left to settle then the solutes particles, either sink or float depending on their densities.

To take these suspended particles out of solution there is an easy method, called filtration.

OC2 separate mixtures using filtration

Apparatus ......


  1. Weigh out an empty clean conical flask
  2. Weigh a piece of filter paper
  3. Fold the Filter paper into a cone
  4. Pour the dirty mixture into the filter funnel (Do not allow the water to go higher than the filter paper)
  5. Allow time for the water to filter through
  6. Allow time for the filter paper to dry
  7. Weigh the Filter paper & residue
  8. Weigh the glass beaker & filtrate.

the Filtrate is the substance that gets through the filter

the Residue is the substance that gets caught in the filter

Coffee Pot

So what other filters do we know about

  • Tea Bag
  • Over Cooker Extractor Head
  • Oil Filter
  • Cigarette Filter

what is the filtrate and residue in each case ??

To set up a filter.

Take a circle of filter paper, fold in half, to make a semi circle.

Fold again to make a quarter circle.

Put a finger in between the 1st 2 folds looking down on the filter paper.

Pull this out to make a cone, place in previously lightly wetted funnel (helps to stick filter paper in).

Slowly pour the mixture into the funnel, do not allow too much to go in at any time.

Allow the filtrate to slowly drip out.

How might you calculate how much residue you caught?

To calculate how much residue caught

Find the mass of the dry filter paper.

Carry out the filtration

Pour through a known mass of water if you want to calculate % suspended solids.


Put in Dry Warm place.

When dry weigh it again,

Subtract the masses, to give the mass of suspended solids

To find the % Suspended solids


Filtration can separate insoluble solids from liquids.