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Separation by a suitable solvent

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Many of the substances we come into contact with mix. Two or more chemicals are combined together in these combinations. In other cases, such a blend may not be possible to employ in both households and businesses. For our purposes, we may just need one (or two) distinct elements of a combination. To make the different combinations usable in our daily lives, we must first separate them into their respective parts.

Separation of Mixture of two Solids

All the mixtures containing two solid substance can be separated by one of the following methods:

  1. By using a suitable solvent
  2. By sublimation
  3. By using a magnet
  4. Gravity Separation
  5. Mechanical Separation

Separation by a Suitable Solvent

In some situations, one component of a combination is soluble in a liquid solvent while the other is not. This variation in solubilities can be utilised to separate the elements of a combination. 

Sugar, for example, is soluble in water but sand is not, therefore a combination of sugar and sand may be separated using water as a solvent. 

Experiment to separate a mixture of sand and salt

  • Apparatus needed: Water, salt, sand, beaker, filter funnel, filter paper, conical flask
  • Experiment: The mixture is taken in a beaker and water is added to it. which is then stirred to dissolve the salt in water. Sand being insoluble in water won’t dissolve. The salt solution containing sand is poured over a filter paper kept in a funnel. Sand remains on the filter paper in the form of a residue while the salt solution is obtained as filtrate in a beaker which is kept below the funnel. By using a similar process, a mixture of sand and sulphur can be separated but here carbon disulphide is to be used as a solution.

Examples of Separation by a Suitable Solvent

  1. Separating a mixture of Sulphur, Salt and Sand: Dissolve the mixture in carbon disulphide. The sulphur will dissolve in it. Now, we have to filter the mixture. Sulphur will go into the filtrate while the sand and salt will be left behind. After leaving the filtrate open, we have to evaporate the sulphur solution. Carbon disulphide will evaporate. Sulphur crystals will be left behind. Then, the residue in water is to be dissolved and the container is to be left undisturbed. Sand will settle down at the bottom. After carrying out sedimentation, sand will be left behind in the container. Now we can evaporate the solution and salt will be left behind
  2. Separating a mixture of Sugar and Salt: Unlike salt, sugar is soluble in alcohol and liquid paraffin, so, we can use ethanol to separate it.  So, we have to add ethanol into the mixture of sugar and salt and use a filter to separate the salt from the mixture. Then, we can evaporate the ethanol-sugar mixture to get the sugar by itself.

Applications of Separation by a Suitable Solvent

  1. Suitable solvents are used to remove hydrocarbon.
  2. It is also used to remove contaminants such as cutting fluids, grease, oil, waxes, and primers.
  3. This method is used in the soap, pharmaceutical and petroleum industries.

Sample Questions

Question 1: What is the matter?


Matter is anything which occupies space and has mass. When someone says that Matter around us is pure, it means that it consists of a single type of particle. In real world, most of the matter around us is a mixture of two or more pure components instead of pure substance. e.g. Milk, sea water etc.

Question 2: Define mixture.


Mixture is a combination of various types of matters. For example- Salt and water solution, iron nails in sand etc. It is of two- types- heterogeneous and homogeneous mixtures. 

Question 3: What are the various types of mixtures?


Mixtures can be classified into two types- homogeneous mixture and heterogeneous mixture. The former is a mixture which possess same properties and combination throughout their masses. while the latter possess different properties and compositions in various parts.

Question 4: Define Centrifugation.


It is used to separate tiny solid particles that pass through a filter paper which is carried out with the process of centrifugation which in turn, is based on the shape and size of particles, viscosity of the medium and speed of rotation. On rotating the rotor, due to centrifugal force the denser insoluble particles separate from liquid and ends up at the bottom of the tube and the liquid gets collected at the top.

Question 5: Define Solute and Solvent.


Solute is the substance that dissolves in a solvent to produce a homogeneous mixture. Solvent is the substance in which a solute dissolves to produce a homogeneous mixture. Solute and solvent both can be a gas, liquid or solid. For example, in a salt and water solution, salt is solute and water is solvent.

Question 6: Explain the separation of a mixture of two Solids by using a suitable solvent.


Here, a mixture of two solids can be separated from each other by using a solvent which will make one of the substance soluble in the solvent, thus separating the two substances. e.g. A mixture of sugar and sand can be separated by using water as a solvent as sugar is soluble in water and sand is insoluble in water. This difference in the solubility of sugar and sand in water is used to separate them.

Question 7: By doing an experiment similar to the one used to separate sand and salt, can we separate salt and sugar solution?


No, the solution can not be separated as both salt and sugar are soluble in water, thus making their separation impossible by using a filter paper.

Last Updated : 16 Sep, 2021
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