Decantation is preferred over filtration when you have a solid that settles to the bottom of a liquid, and you want to separate the clear liquid from the sediment without disturbing the solid. This is useful when the solid particles are larger and heavier, or when the liquid is not needed for further use. Decantation is also a faster method than filtration for separating solid impurities that settle after standing.
Elaboration:
Solid Sedimentation:
Decantation is ideal when the solid particles settle out of the liquid due to gravity or other forces, forming a clear liquid above the solid.
Efficiency:
Decantation is a quicker separation method than filtration because it doesn’t require the use of filter paper or other filtering devices.
Mixtures of Immiscible Liquids:
Decantation can also be used to separate two immiscible liquids, like oil and water, where the less dense liquid can be poured off the top, leaving the heavier liquid behind.
Applications:
Examples of decantation include separating mud from water, oil from water, or separating the clear liquid from settled sediment in canned vegetables.
When filtration is preferred:
Fine Particles:
If the solid particles are very fine and would pass through a filter, filtration is necessary to remove them from the liquid.
Solids that Don’t Settle:
If the solid particles don’t readily settle to the bottom, filtration is needed to remove them from the liquid.
When Liquid is Needed:
If the liquid needs to be purified, filtration is the better choice as it allows for the removal of solid impurities while retaining the liquid.