NCERT Solutions for Class 12 Chemistry Chapter 6 – General Principles and Processes of Isolation of Elements
NCERT Solutions for Class 12 Chemistry Chapter 6 – General Principles and Processes of Isolation of Elements provides all answers to the questions asked in this Chapter in detail. This Chapter explains the terms ores, minerals, concentration, benefaction, calcination, roasting, and refining involved in metallurgy. Further, this chapter covers the principles of oxidation and reduction applied to extraction processes, thermodynamics in the extraction of some specific metals. This Chapter also explains how some of the oxides are easier to reduce and why some of the reducing agents are favoured over others.
In this Chapter, there are a total of 27 questions asked at the end. All of these questions have been designed to cover all the concepts taught in NCERT Solutions Class 12 Chemistry Chapter 6. The direct and applicative questions are based on principles and techniques of extraction, thermodynamic and electrochemical principles used for metallurgy, reactions involved in different extraction processes and reasons lying behind certain principles.
All of these questions have been answered accurately in Class 12 Chemistry Chapter 6 – General Principles and Processes of Isolation of Elements. The Solutions follow all the guidelines given by CBSE and NCERT. They are easy to understand, precise, and a hundred percent accurate.
NCERT Class 12 Chemistry Chapter 6
NCERT Solutions for Class 12 Chemistry Chapter 6 – General Principles and Processes of Isolation of Elements encompass all the topics of this Chapter. They give you a comprehensive understanding of all the concepts covered in this Chapter. The main topics covered in this Chapter are as follows.
- Occurrence of Metals
Here you learn that we need metals for many purposes in our daily lives. This requires us to extract them from their natural reservoir minerals and ores, the latter being the commercially useful one.
- Concentration of Ores
This part of the NCERT CBSE Class 12 Chemistry Chapter 6 tells that the first step in extraction of metals is the removal of unwanted material from ores by either concentration, dressing or a benefaction process.
Some of the important procedures taught in this section include magnetic separation, gravity separation, hydraulic washing, froth floatation method, and leaching. This Chapter also tells you that metallurgy of silver and gold is based on leaching with a dilute solution of metal cyanide.
- Extraction of Crude Metal from Concentrated Ore
This part of the CBSE NCERT Class 12 Chapter 6 tells you that concentrated ore is converted to a form which can be easily reduced further. Oxides are easy to reduce after concentration ores are converted to oxides, and then that oxide is reduced to obtain metal.
This part further tells you that conversion to oxide can be done by calcination. Calcination is heating the ore so that volatile matter escapes leaving behind oxide and roasting where ore is heated in a regular supply of air to get oxides, and the latter is used mainly for sulphide ores.
Here you will also learn that the oxides such prepared are reduced using a reducing agent like C or CO or another metal to obtain pure metal. The suitable reducing agent is decided by Gibbs energy interpretation.
- Thermodynamic Principles of Metallurgy
This part of NCERT Class 12 Chemistry Chapter 6 lets you learn the role of thermodynamic concepts in metallurgical transformations and Gibbs energy consideration.
Here you will learn that when metal oxide reacts with a reducing agent to give the free metal, the reducing agent is oxidised, the net Gibbs energy change is negative for these two reactions, which becomes more negative on increasing reaction temperature. This part further tells you that change in physical states like solid to liquid or to gas and formation of gaseous states further leads to lowering Gibbs energy.
This portion of the Chapter also tells you that the Ellingham diagram is a graphical representation of this concept where ΔGθ is plotted against temperature, T, for such oxidation-reduction reactions at various temperatures. This is used immensely in the extraction of iron and copper metals.
- Electrochemical Principles of metallurgy
This part of the CBSE NCERT Class 12 Chemistry Book teaches you how electrolysis is performed for reduction of molten metal salts. This is based on certain electrochemical principles. Isolation of certain metals like Al, Ag, Au uses the concept of electrode potential, where the sum of electrode potential is kept positive in order to achieve a negative Gibbs energy change.
It further tells you that extraction of aluminium from its bauxite ore is usually performed by leaching it with sodium hydroxide to give sodium aluminate. Sodium aluminate is then separated and neutralised to give back the hydrated oxide, which is then electrolysed using cryolite as flux.
This part of the Chapter teaches you that extraction of non-metals is based on oxidation by an electrochemical process. Chlorine is obtained by this method.
In this portion, you learn that metals extracted still contain some impurity and obtaining them in the highly pure state needs several techniques of refining. The different techniques depending upon the differences in the properties of the metals and the impurity are distillation, liquation, electrolytic refining, zone refining, vapour phase refining and chromatographic methods.
You come to know here that distillation and liquidation are methods opted for low boiling metals. In electrolytic refining pure metal strips are used as cathode and impure metal as the anode, they are put in an electrolyte of salt of the same metal.
This part also explains that Zone refining utilises the principle that when molten impurities remain in melt being more soluble than the solid-state of metal separating out. Metal is converted into vapour phase for purification in vapour phase refining, Mond’s process used for refining Ni is one of its alterations.
Further, it tells you about chromatographic techniques which are based on differential adsorption of different components of a mixture on the adsorbent phase when the mixture is run through the adsorbent with the help of a mobile phase.
- Uses of Aluminium, Copper, Zinc and Iron
This part of the Chapter discusses the use of metals in a wide variety of places important in our daily lives.
CBSE NCERT Class 12 Chemistry Chapter 6 Exercise
Our NCERT Solutions for Class 12 Chemistry Chapter 6 – General Principles and Processes of Isolation of Elements consists of 27 questions covering the important topics learnt here. The constituents of the exercise have been listed below.
- Questions 1 and 3 are reason-based questions.
- Question 2 asks you about the role of depressant in froth floatation.
- Questions 4, 10, 11 are explanatory questions asking about zone refining and column chromatography.
- Questions 5, 20, 21, 22, 23 and 27 ask you to apply the concept of Ellingham diagram.
- Question 6 is based on electrolytic extraction of copper.
- Question 7 is based on reactions happening in the extraction of iron through a blast furnace.
- Question 8 is based on the chemistry involved in zinc extraction.
- Question 9 asks you about the role of silica in metallurgy of copper.
- Question 12 needs you to tell a method for Ni refining.
- Questions 13 and 25 are based on techniques used in the extraction of Al from bauxite.
- Questions 14 to 16 are differential questions.
- Questions 17 and 19 are based on copper extraction.
- Questions 18 asks about the role of cryolite in Al extraction.
- Question 24 is about electrolysis of molten NaCl.
- Question 26 is a direct question asking about the principles lying behind the given methods of refining metals.
There are 8 intext questions asked in CBSE NCERT Class 12 Chemistry Chapter 6 to which best answers have been provided in our Solutions.
Benefits of NCERT Solutions for Class 12th Chemistry Chapter 6 – General Principles and Processes of Isolation of Elements
The process of learning and revising from NCERT Solutions for Class 12 Chemistry Chapter 6 – General Principles and Processes of Isolation of Elements is highly beneficial for you. Some of the advantages are as follows –
- They are easy to understand and drafted in a simple language.
- They are all-encompassing yet concise Solutions that help you learn and revise quickly during your board exams.
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They help you to achieve higher marks in class 12th board exams and prepare for the competitive exams you are planning to take.