General Principles and Processes of Isolation of Elements Class 12th Notes - Free NCERT Class 12 Chemistry Chapter 6 Notes - Download PDF

The chapter General Principles and Processes of isolation of elements is a very important inorganic chemistry chapter. This is a chapter with practical applications too. The NCERT Class 12 Chemistry chapter 6 notes provide a summary of the chapter General Principles and Processes of Elements Isolation. General Principles and Processes of isolation of elements Class 12 notes covers the topics occurrence of metals, concentration of ores, extraction of crude metal, Ellingham diagram, extraction of iron, refining etc. Class 12 is stressful, and many students find Chemistry to be a tough subject to study. Many students find inorganic chemistry to remember.

The NCERT Class 12 Chemistry chapter 6 notes is given in a straightforward manner, allowing students to quickly learn the entire syllabus of the chapter.

Also, students can refer,

• NCERT Notes Class 12 Chemistry
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  Elements
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  Isolation of Elements

NCERT Class 12 Chemistry Chapter 6 Notes-Topic 1

Occurrence of metals

Minerals are naturally occurring chemical components in the earth's crust that can be obtained by mining. Metals may or may not be profitable to extract from them. Ores are rocky materials that contain a significant amount of mineral to allow the metal to be mined profitably or economically. Gangue refers to the earthy or unwanted elements found in ore.

NCERT Class 12 Chemistry Chapter 6 Notes-Topic 2

Metallurgy

Metallurgy refers to the complete scientific and technological process of isolating metal from its ores. Different parts of metallurgy include

1. Crushing and grinding

For processing, the metal ore is first pulverised or crushed into powder. Crushing or grinding is the term for this procedure

2. Concentration of ores

Dressing, concentration, or benefaction are terms used to describe the process of removing unwanted contaminants from ore. Hydraulic washing, electromagnetic separation, froth flotation, and leaching are all options.

3. Isolation of crude metal from the ore

The unrefined metal is separated in two steps: the ore is converted to oxide and then reduced to metal. Smelting, self-reduction, metal displacement, or electrolytic reduction are all methods for converting metal oxide to metal oxide

4. Refining or purification of the metal

Finally, the obtained unrefined metal must be purified before it is used. Liquation, distillations, zone refining, chromatography, and electrolysis can all be used to accomplish this.

NCERT Class 12 Chemistry Chapter 6 Notes-Topic 3

Concentration of Metals

It includes a number of processes that are dependent on the physical properties of the metal complex and the presence of impurities (gangue). The type of metal, the facilities available, and environmental variables are all taken into account.

• Hydraulic washing/ Gravity separation

It is based on the density differences between ore and gangue particles. Lighter impurities are washed away while heavy ores are left behind when ore is washed with a stream of water under pressure.

• Magnetic separation

The difference in magnetic and non-magnetic characteristics of two ore components is used in this procedure. To extract tungsten ore particles from cassiterite, this process is utilized. It's also used to separate unwanted gangue from magnetite , chromite and pyrolusite.

• Froth flotation

It is built on the idea that sulfide ores are wetted preferentially by pine oil, fatty acids, xanthates, and other similar substances, whereas gangue particles are wetted by water. Collectors are used to improve the mineral particles' non-wettability. Cresols, aniline, and other froth stabilizers are used to keep the froth stable. It is possible to separate two sulfide ores by altering the percentage of oil to water or by adding depressants if two sulfide ores are present.

• Leaching (chemical separation)

It is a method of treating ore with an appropriate solvent that dissolves the ore but not the contaminants. eg : Purification of bauxite

NCERT Class 12 Chemistry Chapter 6 Notes-Topic 4

Extraction of Crude Metal

1. Conversion of ore into metal oxide

Oxide ore is simpler to reduce than sulfide or carbonate ore. Any of the following methods should be used to convert the provided ore into oxide.

• Roasting

It is a method of converting ore into oxide ore by heating it in a regular supply of air at a temperature below the metal's melting point. Roasting converts sulfide ores into oxide. It is also utilized to get rid of contaminants like volatile oxides.

Eg: 2 ZnS + 3 O₂ yields→ 2 ZnO + 3 SO₂

• Calcination

It is a method of converting carbonate ores into oxides by heating ore in a small amount of air. It I 's also used to get rid of moisture and volatile contaminants.

Eg : CaCO₃ Heat→ CaO + CO₂

2. Reduction of metal oxide to metal

3. Reduction is the process of turning metal oxide to metal. Depending on the reactivity or reducing power of the metal, an appropriate reducing agent is required. Carbon or carbon monoxide, as well as other metals such as Al, Mg, and others, are commonly utilized as reducing agents.

NCERT Class 12 Chemistry Chapter 6 Notes-Topic 5

Ellingham Diagram

Ellingham diagrams are plots of change in Gibbs free energy of formation of oxides of elements vs. temperature. It gives a good concept of how to choose a reducing agent for oxide reduction. These diagrams help to determine whether or not a thermal reduction of an ore is feasible. For a reaction to be feasible, Gibbs free energy change must be negative at a particular temperature. Ellingham Diagrams have the drawback of not taking the kinetics of reduction into account, which means that the rate of reduction cannot be predicted.

NCERT Class 12 Chemistry Chapter 6 Notes-Topic 6

Extraction of Iron

The reduction of oxides occurs in various zones of the blast furnace.

C + 2O₂ yields→ 2 CO

FeO + CO yields→ Fe + CO₂

1. Lower temperature range ( 500 K-800 K)

3 Fe₂O₃ + CO yields→ 2 Fe₃O₄+CO₂

Fe₂O₄ + 4 CO yields→ 3 Fe+4 CO₂

Fe₂O₃ + CO yields→ 2 FeO+ CO₂

2. Higher temperature range ( 900 K- 1500 K)

C + CO₂ yields→ 2 CO

FeO + CO yields→ Fe + CO₂

3. Limestone decomposes to CaO and CO₂

CaCO₃ yields→ CaO + CO₂

4. Calcium silicate is formed when silica (impurity) interacts with CaO to generate slag. It floats on top of molten iron, preventing iron oxidation.

CaO + SiO₂ yields→ CaSiO₃

Pig iron is the iron produced in a blast furnace. It is made of impure iron and contains 4% carbon, as well as tiny amounts of S, P, Si, and Mn. It may be moulded into a wide range of shapes. Cast iron is prepared by melting pig iron, scrap iron, and coke together with a hot air blast. It has a carbon content of approximately 3%. It is exceedingly brittle and rigid. Wrought iron is the purest type of iron available for commercial use. It's also referred to as malleable iron. Pig iron is oxidatively refined in a reverberatory furnace lined with haematite, which converts carbon to carbon monoxide.

NCERT Class 12 Chemistry Chapter 6 Notes-Topic 7

Refining

It involves converting impure metal to pure based on the nature of the metal

• Distillation

It is a method for purifying metals with low boiling points, such as zinc, mercury, sodium, and potassium. Impure metal is heated to convert it to vapours, which then condensate to form pure metal, which is obtained as distillate.

• Liquation

This procedure can be used to purify metals with impurities with melting points higher than the metal. Sn metal can be refined using this process. Tin with impurities of iron was heated on the top of a slanting furnace. Tin melts and slides down the sloped surface, leaving no iron behind and yielding pure tin.

• Electrolytic refining

Impure metal is employed as the anode, pure metal is used as the cathode, and a soluble metal salt is used as the electrolyte in this technique. Impure metal generates metal ions when an electric current is run through it, which are then discharged at the cathode, producing in pure metal.

• Zone refining

It is based on the fact that impurities are more soluble in the melt than in the solid state of the metal. At one end of the impure metal rod, circular heaters are used to heat the impure metal. The molten zone continues along with the heater, picking up impurities along the way, until it reaches the other end, where it is discarded. Out of the melt, pure metal crystallizes. The procedure is done multiple times, with the heater moving in the same direction each time. It is employed in the purification of semiconductors such as B, Ge, Si, Ga, and In.

• Vapour phase refining

Metal is transformed to a volatile chemical and collected in this procedure. After that, it is dissolved into pure metal.

• Chromatographic method

It is based on the principle of chromatography, which is based on differential adsorption on an adsorbent for separation or purification.

These topics can be studied from General principles and processes of isolation of elements Class 12 notes pdf download.

Significance of NCERT Class 12 Chemistry Chapter 6 Notes

General Principles and Processes of isolation of elements Class 12 notes will surely assist students in tackling all little and significant problems linked to this course to a great extent Also, NCERT Class 12 Chemistry chapter 6 notes are very helpful to study the main topics of the Class 12 CBSE Chemistry Syllabus. This chapter is important for various competitive exams like VITEEE, BITSAT, JEE Main, NEET etc.

NCERT Class 12 Chemistry chapter 6 notes also helps the students for the preparations of these exams. Students can download Class 12 Chemistry chapter 6 notes pdf download and use it for the offline mode preparation.

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