Centrifugation
Explanation
Centrifugation is a separation technique that utilizes centrifugal force to separate particles from a solution based on their size, shape, density, and viscosity of the medium. It is the primary method used for separating colloidal particles, which are suspended in a medium but are too small to be separated by ordinary filtration.
- Simple filtration is incorrect: Simple filtration relies on a filter medium (like filter paper) with specific pore sizes. Colloidal particles, such as the fat globules in milk, are smaller than the pores of standard filter paper and pass through easily, making filtration ineffective.
- Evaporation is incorrect: Evaporation is used to separate a non-volatile dissolved solid from a volatile liquid (solvent). Applying this to milk would result in the loss of water content rather than the separation of cream from the milk.
- Centrifugation is correct: Centrifugation operates on the principle of density difference. When milk is spun at high speeds, the denser components (skimmed milk) are forced outward or to the bottom, while the lighter components (cream/fat) remain at the center or float to the top, allowing for separation.
- Magnetic separation is incorrect: Magnetic separation is applicable only when one component of the mixture possesses magnetic properties (e.g., separating iron from sand). Components of milk are non-magnetic.
Key Takeaway: Centrifugation is the most appropriate technique for separating emulsions and colloids (such as milk or blood) where components differ in density but are too fine for filtration.