Question

Write principle and application of following methods of separation
1. Separating funnel
2. Centrifugation
3. Paper chromatography

Answer 1

Hint: There are different methods of separation that will take part in separation at molecular level. These separation methods are based on the separation of molecules as per its different solubility in solvent of same solute. These methods are used to know different types of molecules present in the given solution.

Complete answer
Now, let us discuss the principle and application of given methods of separation.
1. Separating funnel: The lab apparatus majorly used for the separation of the two immiscible solutes in the given mixture. For example, oil and alcohol. It is applicable to separate the solvent which are immiscible and which cannot be separated by steam distillation. This method is useful for liquids only.
2. Centrifugation: It is used to separate the heavy particles and lighter particles in the solution by rotating test-tubes filled with solution which contains precipitates. The method is widely used to separate suspension. A type of solution that contains particles which are floating in the solution and will take longer time to settle down. The method is applicable to the suspension or colloid in which the solute is solid and needs to be separated from the solution. The centrifugation is generally used for the particles of solid which are nanoparticles.
3. Paper Chromatography: It is the chromatographic technique that uses paper to separate the solute as per the rate of its solubility. The paper is marked with the one-inch line at the bottom and the drop of the solution is kept on that line then that paper is dipped into the solvent like water or alcohol which can dry easily and time is noted till the solvent reaches the top of the paper. The molecules will raise with the solvent particles as the solvent particles travel up on the paper. The molecule which is least soluble will remain at the bottom line and the particles which are having highest solubility will travel away from the bottom line. Paper chromatography is applicable to the liquid solution for separation of multiple solutes present in the solution.

Note:
The different separation technique works on different principle
(a) Insolubility of the two solutes
(b) Difference in weight of the particles.
(c) Difference in the solubility of solute in solution in which the paper is dip.
The techniques should be chosen appropriately because by choosing the wrong technique we won’t get the appropriate separation.