Question

In order to separate a mixture of sand and salt, which one of the following four sequences of processes has to be used?
1. Evaporation, sedimentation, decantation, filtration
2. Decantation, sedimentation, evaporation, filtration
3. Sedimentation, decantation, filtration, evaporation
4. Filtration, decantation, evaporation, sedimentation

Answer 1

Correct Answer - Option 3 : Sedimentation, decantation, filtration, evaporation

Concept:

• Evaporation, Sedimentation, Decantation, and Filtration are the separating techniques used in our day to day life.
• We can find a mixture of components and to obtain a pure component we need to adopt a few techniques for purification and separation. 

Explanation:

Sedimentation:

• I t is defined as the separation process in which solids are separated from the liquid.
• All the solids settle down at the bottom of a beaker and on top, a clear layer of liquid is obtained. 
• Sedimentation is a process by which heavier impurities present in liquid settle down at the bottom of the container containing the mixture.
• The process takes some amount of time.
• Example:
  • In the sand and salt mixture, the sand settles at the bottom of the beaker to form saltwater at the top.

Decantation:

• Decantation is a process to separate mixtures by removing a liquid layer from the solids deposited from a solution.
• This is done by pouring out the clear upper layer of liquid.
• Example:
  • After the sand settling at the bottom the relatively clean water containing salt is poured out of the beaker.

Filtration:

• It is defined as the separation process in which insoluble impurities are separated from the solution.
• Filtration is done with the help of filter paper.
• Example:
  • The above mixture filtration is used here to remove any solid suspended sand particles from the liquid. 

Evaporation:

• It is the process by which water changes from a liquid to a gas or vapour.
• Boiling is the process in which a liquid is converted into its vapour when heated to its boiling point.
• In the evaporation separation technique, the water evaporates leaving behind the soluble portion.
• Example:
  • In the above mixture, the water is evaporated leaving behind salt crystals. 

Thus, in order to separate a mixture of sand and salt, the four sequences of processes to be used are sedimentation, decantation, filtration and evaporation.