We can use various methods to separate the mixtures. Here, we explore centrifugation the widely used methods to separate the mixture.
Centrifugation method separate two materials of different densities by spinning them together. When insoluble particulates are found in a dissolved solution, they are better used to isolate products of similar densities.
Principle: The centrifugal acceleration causes denser particles to move outward in the radial direction. At the same time, less dense particles being displaced and move towards the centre.

  • The fine insoluble solids from a solid-liquid mixture can be separated in a machine and called a centrifugate in the process.  
  • The machine rotates at a very high speed. The heavier solid particles move down on being rotated due to centrifugal force, and the lighter liquid remains at the top.
Let us now check how can we separate the milk from cream using centrifugation technique:

Step 1: Fill a test tube halfway with full-cream milk.

Step 2: Centrifugate it for two minutes in a centrifugate pump. If you don't have access to a centrifuging machine at school, you can do this task at home using a milk churner.

Observation: A heterogeneous solution is obtained after centrifugation.

Result: The denser milk settles at the bottom, and the lighter cream floats on the top.
  • In pathological lab centre, they use this principle to separate the blood cells from the blood samples. 
  • We can use this process to separate the cream from the milk.
  • Washing machines follow the same principle to separate the water from wet clothes.