Separation of Substances: Class 6 Science NCERT Chapter 5

Key Features of NCERT Material for Class 6 Science Chapter 5 –  Separation of Substances

In the previous chapter of NCERT class 6 Science: Sorting Materials into Groups, you studied the properties of materials that things are made up of. You also learnt the classification of these materials according to their properties. In this chapter: Separation of Substances, you will learn different methods of separation and to remove impurities. You will also study a few examples of these techniques.

Quick revision notes

Impurities:

These are the undesirable particles present in a substance making it unclean. 

Mixtures:

Substances which contain more than one segment blended in any proportion are called mixtures. For instance, the air is a mixture of numerous gases like nitrogen, oxygen, carbon dioxide, dust particles, and so forth. 

Homogeneous Mixtures:

The mixtures wherein the particles of the substances present can’t be seen are called homogeneous mixtures. For instance, solutions for sugar, water, air, cold beverages, and so on. 

Heterogeneous Mixtures:

The mixtures where particles of the substances present can be seen effectively are called heterogeneous mixtures. For instance, water in oil, dust in the air.

The requirement for Separation:

We complete the separation of the segments of a mixture or a polluted substance with the accompanying purposes: 

  • To expel the unuseful or unsafe segment. 
  • get a useful segment. 
  • To expel impurities for getting an unadulterated example. 

Principle of separation 

  • The substances present in a mixture hold their unique properties like molecule size, thickness, liquefying point, breaking point, instability, and so on. 
  • We utilize the difference in any of these properties in the parts of a mixture to isolate them. 

Methods of Separation:

Handpicking, winnowing, sieving, magnetic separation, sedimentation, loading, decantation, filtration, evaporation, sublimation, churning, distillation, and so forth., are some regular methods of separation. 

Churning (or Centrifugation):

It is the procedure of separation of the lighter particles of a suspended solid from a fluid. For instance, to acquire butter from the curd or milk. 

Condensation:

The procedure of transformation of water fume into liquid is called condensation. 

Crystallization:

The procedure of crystallization is utilized for acquiring unadulterated glasslike substance from unclean example. 

Decantation:

It is the exchange of clean fluid from one vessel to the next without disturbing the settled (sedimented) particles. 

Evaporation:

It is the way toward expelling water (or moisture) from a mixture either by warming on fire or direct daylight. For instance, salt from ocean water is acquired by this technique. 

Filtration:

Filtration is utilized to isolate strong particles from a fluid by making the mixture go through a channel paper. 

Handpicking:

This technique is utilized for isolating little particles of soil, stone, husk, and so on., from the grains of wheat, rice, beats, and so forth. 

Loading:

It is the procedure of quicker sedimentation by suspending alum to a fluid. 

Sedimentation:

It is the way toward settling of overwhelming strong particles in a mixture at the base of the vessel. 

Sieving 

  • Sieving is utilized when two segments of a mixture have diverse molecule sizes. 
  • it permits the fine particles to go through the gaps of the strainer, while the greater particles stay on the sieve. For instance, sieving of wheat flour, sieving of sand at building locales. 

Saturated solution:

A solution wherein, not any more solvent substance can be dissolved at room temperature is called a saturated solution. 

Solution:

When a solvent substance is dissolved totally in a fluid (for eg sugar in water), a homogeneous mixture is framed. It is known as a solution. 

Threshing:

The procedure that is utilized to isolate grain from stalks is threshing. 

Winnowing:

Winnowing can be utilized to isolate lighter and heavier segments of a mixture. For instance, to isolate husk from grain with the assistance of air. 

Methods Of Separation in detail: 

Various methods are utilized for isolating various substances that are combined. Let us find out about some regular methods that are utilized. 

Threshing: 

Grains or seeds of plants like rice and wheat fill in as sources of food. The flour (atta) that is utilized for making chapattis is produced using wheat grains. After these yields have been collected or cut, the grains should be isolated from the stalks (the dried stems). This is achieved by threshing. 

The method of beating harvests to isolate the grains from the stalks is called threshing. It is done physically (by hand) or with the assistance of machines. Manual threshing is finished by holding a heap of yield and beating it on a stone or a hard surface (Fig. 3.1). This slackens and isolates the grain from the tail. Once in awhile, threshing is additionally done by pulverizing the reaped stalks utilizing bullocks. 

Threshing is likewise finished with the assistance of machines like the combine harvester (Fig. 3.2). Threshed grains may, in any case, contain seed covers and bits of leaves or stem ( called chaff). These are isolated by winnowing. 

Separation of Substances: wheat

Separation of Substances: threshing

Winnowing: Separation of Substances: Winnowing

The technique used to isolate chaff from the grain by wind or blowing air is called winnowing. 

The mixture of debris and grain is taken in a winnowing container (Fig. 3.3). The farmer remains at a more elevated level and lets the mixture tumble to the ground. 

The grain, being heavier, falls vertically through the lighter chaff is diverted by the breeze and structures a different pile away from the grain. 

The isolated refuse is utilized as feed for dairy cattle. The heading of the breeze assumes a significant job during the time spent winnowing. 

Hand-picking: 

Rice, pulses, wheat, and so on., that we purchase from the market may contain impurities (undesirable or unsafe particles) as little stones, undesirable grains, and so forth. Regularly, these impurities appear to be unique from the food thing and can be spotted without any problem. The technique for separation utilized in such a case is hand-picking (Fig. 3.4).

  •  This strategy is favoured when 
  • the amount of the mixture is little,
  • the undesirable substance is available in littler amounts,

 and the size, shape, or shade of the undesirable substance is unique in relation to that of the useful one. 

Separation of Substances: Hand picking

Sieving: 

On the off chance that the parts of a mixture are of various sizes, they can be isolated by sieving (Fig. 3.5). The littler part goes through the pores of the sieve and the bigger segment (stones or husk) is left behind in it. This technique is utilized in certain homes to isolate wheat bran (the greater particles) from flour. 

Be that as it may, sieving wheat flour isn’t prudent as wheat bran, which is expelled during sieving, is rich in nutrients and is additionally a rich is smarter to evacuate obvious impurities by handpicking. 

The way toward sieving is additionally used to isolate rocks and stones from the sand at building construction sites. The stones and rocks present in the mixture stay in the strainer and the fine sand particles go through the gaps of the sieve.

Separation of Substances: Sieving

Sedimentation and Decantation: 

Have you seen beats being washed in your home? At the point when heartbeats are kept in a bowl of water, they settle down as they are overwhelming. Be that as it may, earth, bugs, bits of straw, and other lighter impurities glide at the top. The water, which contains these impurities, is then spilt out and disposed of. This procedure includes two methods: sedimentation and decantation. 

The way toward isolating insoluble solids, suspended in a fluid, by permitting them to settle down is called sedimentation. 

The solid particles that settle down during sedimentation are sediments. 

Sedimentation and Decantation The method of pouring out the clear upper fluid without bothering the residue is called decantation. 

The fluid over the sediments is a supernatant

A mixture of sand and water can likewise be isolated by sedimentation and decantation. 

The mixture is left undisturbed for quite a while. 

Sand, being heavier, settles down and water is emptied out into a different holder. 

Filtration: 

The procedure by which two substances (an insoluble solid and fluid) are isolated by going the mixture through a filtering device is called filtration. 

Filtration is usually utilized in our homes. For instance, in the wake of making tea, we sift through the tea leaves utilizing a filter. Filtration is likewise utilized to remove the pulp from fruit juice. Water may likewise contain strong impurities, which can be expelled by filtration. 

During filtration, the insoluble strong is held in the filtering device and the fluid goes through it. It is significant that the particles of the insoluble strong are greater than the openings in the filtering device for them to be held in it. A filter paper is a filtering device that has fine pores in it. 

Filtration: Evaporation

Condensation: 

The procedure where gas changes into a fluid is called condensation. Condensation is something contrary to evaporation. In nature, water fume noticeable all around consolidates to shape its fluid structure, the dew. Condensation happens just when water fume hits a cold surface. 

Solution And Solubility: 

At the point when some salt is added to water and mixed, the salt vanishes. This is on the grounds that the salt has been dissolved completely up in the water. 

Solution And Solubility

Dissolving is where substances blend totally with the fluid they have been added to. 

Not all substances dissolve completely in the water. Just some substances, Salt dissolves completely in water. like salt and sugar, dissolve in water and are known as solvent substances. Substances like chalk and sand don’t dissolve water and can be seen so they are known as insoluble substances. 

The substance that dissolves is known as the solute and the substance wherein the solute dissolves are solvent. The result of this is a mixture is known as the solution. In this manner, solute + solvent = solution. 

E.g., sugar + water = sugar solution.

Solution And Solubility

On the off chance that we continue adding spoonfuls of sugar to water and mix the solution each time, what will occur after some time? We will see a few grains of sugar at the base of the solution. This shows no more sugar can be dissolved. We state that the solution is saturated (Fig. 3.7). 

A saturated solution is a solution where more solute cannot be dissolved. 

In any case, consider the possibility that we heat the solution. Can we at that point dissolve that ‘extra’ sugar present in the saturated solution? 

Indeed, we can build the solubility of a solute by warming the solution. Solubility is the capacity of a substance to get dissolved in a given fluid. The amount of a substance that can dissolve in high temp water is substantially more when contrasted with that in cool water. 

Some different elements can enhance the solubility of a solute. 

Stirring:

We can watch this by taking two glasses of water and adding a spoonful of sugar to each glass. At that point, we keep one glass undisturbed and mix the other. Sugar dissolves quicker when the solution is stirred. 

Solute in powdered structure:

We can watch this by taking two glasses of water and including an entire sugar cube in one glass and powdered or squashed sugar cube in the other. Sugar in the powdered structure dissolves first. 

Various substances dissolve in various measures of water while making a saturated solution. 

Threshing :

The way toward beating harvests to isolate seeds from the stalks is called threshing. 

Winnowing:

The strategy used to isolate chaff from the grain by wind or blowing air is called winnowing. 

Sedimentation :

The way toward isolating insoluble solids suspended in a fluid by permitting them to settle down is called sedimentation. 

Decantation:

 The way toward pouring out the clear upper fluid keeping the sediments undisturbed is called decantation. 

Filtration :

The procedure by which an insoluble strong is isolated from a fluid by making the mixture go through a filtering device is called filtration. 

Saturated solution:

A solution that cannot dissolve solute any more is known as a saturated solution. 

Hand-picking includes physically throwing little stones, bugs, and so on from the grains. 

Sedimentation and decantation are utilized to isolate an insoluble solid from a fluid. 

Insoluble solid impurities present in water can be expelled by filtration. 

Normal salt can be isolated from seawater by evaporation. 

The solubility of a solute can be expanded by warming the mixture or it can likewise be expanded by including the solute in the powdered structure.

Threshing :

The way toward beating harvests to isolate seeds from the stalks is called threshing. 

Winnowing:

The strategy used to isolate chaff from the grain by wind or blowing air is called winnowing. 

Sedimentation :

The way toward isolating insoluble solids suspended in a fluid by permitting them to settle down is called sedimentation. 

Decantation:

 The way toward pouring out the clear upper fluid keeping the sediments undisturbed is called decantation. 

Filtration :

The procedure by which an insoluble strong is isolated from a fluid by making the mixture go through a filtering device is called filtration. 

Saturated solution:

A solution that cannot dissolve solute any more is known as a saturated solution. 

Hand-picking includes physically throwing little stones, bugs, and so on from the grains. 

Sedimentation and decantation are utilized to isolate an insoluble solid from a fluid. 

Insoluble solid impurities present in water can be expelled by filtration. 

Normal salt can be isolated from seawater by evaporation. 

The solubility of a solute can be expanded by warming the mixture or it can likewise be expanded by including the solute in the powdered structure.

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