Question

Why do we decant the supernatant fluid in Lab ?

a) To isolate the solid precipitate
b) To mix the solution
c) To speed up the reaction
d) To evaporate the solvent

Answer 1

In lab, we decant the supernatant to isolate the solid precipitate from a solution, separating it from the liquid supernate after sedimentation or centrifugation.

Step-by-step explanation:

We decant the supernatant fluid in lab primarily to isolate the solid precipitate. Decanting involves carefully pouring off the supernatant liquid and leaving the solid material behind, usually after sedimentation or centrifugation.

This process separates a solid precipitate from a liquid supernate in which the particulate matter is dispersed. For instance, after forming a precipitate in an aqueous solution, decanting the liquid helps recover the solid component more efficiently.

Crystallization is another method that may follow decantation, where a compound is purified as it crystallizes out of the solution when conditions no longer favor its solubility. This is often used when synthesizing compounds to remove impurities. Lastly, distillation is a technique that separates components based on differences in volatility but is not related to decanting, which is a simpler physical separation method.