Answer: All India 2013) Question 49. Answer: What role is played by CO2 in getting pure alumina (A1l2O3) in the extraction of aluminium? Then the end with impurities is cut off. (i) Zone refining of metals: This method is based on the principle that impurities are more soluble in the molten state of the metal (the melt) than in the solid state. Acidic silica is added during smelting to separate the FeO from the mixture. Answer: The subject matter experts create the solutions with the aim of helping students to score well in the board exams. NCERT … (Delhi 2009) Q7. Answer: Af cathode : (reduction) Answer: It is used for the con­centration of carbon­ate ores. (ii) Electrolytic refining : Here the impure metal is made to act as anode and a strip of the same metal in pure form is used as cathode. Mond’s process is a technique used to refine nickel. Answer: Outline the principles behind the refining of metals by the following methods : Oxidation : 4Au + 8NaCN + O2 + 2H2O → 4Na [AU(CN)2] + 4NaOH It has slightly lower carbon content (about 3%) and is extremely hard and brittle. (c) Chromatography. (in) What is the role of coke in the extraction of » iron from its oxides? Here limestone (CaCO3) decomposes into CaO and CO2. (Comptt. Delhi 2013) (Comptt. Nickel is heated in a stream of carbon monoxide forming a volatile complex, nickel tetracarbonyl which is further subjected to higher temperature so that it is decomposed to give pure nickel. Zone refining: It is based on the principle that the impurities are more soluble in molten state than in the solid state of the metal. In zone refining, a moving circular heater slowly moves over an impure metal rod/ bar. Mond process for refining nickel. ZnC03 \(\stackrel{\Delta}{\longrightarrow}\) ZnO + C02↑. Hydrometallurgy; Copper is extracted from low grade ores and scrap. Free PDF download of NCERT Solutions for Class 12 Chemistry Chapter 6 General Principles and Processes of Isolation of Elements solved by Expert Teachers as per NCERT (CBSE) Book guidelines. (Comptt. The type of questions that will be asked from NCERT Class 12 Chemistry Chapter 6 are displayed in the below provided NCERT Exemplar Class 12 Chemistry Chapter 6. Also access the PDF version and download the same. Name the method used for the refining of Nickel metal. (ii) Zone refining of metals: This method is based on the principle that impurities are more soluble in the molten state of the metal (the melt) than in the solid state. Mond process is used for refining of nickel and Van-Arkel method is used for refining of titanium. (a) Write the principle involved in the ‘vapour phase refining’ of metals. As a result, pure metal crystallizes out of the melt and the impurities pass to the adjacent molten zone. (ii). 20.01.2021 Leica Camera AG IT Business Process Manager Operations & Logistics (m/w/d) Wetzlar 20.01.2021 Wildeboer Bauteile GmbH Systemadministrator (m/w/d) Weener 20.01.2021 SUSS MicroTec Lithography GmbH Software Engineer / IT-Administrator (m/w/d) für die IT-Integration Sternenfels Cu2+ + 2e– → Cu. Delhi 2014) The ZnO is made into brickettes with coke and clay and heated above 673 K so that the reduction process goes to completion. Write down the reactions taking place in different zones in the blast furnace during the extraction of iron. (ii) Chromatographic method : It is based on the principle that different components of a mixture are differently adsorbed on the adsorbent. Question 18. Answer: When dealing with low grade copper ores, bacteria or acids are used in the presence of air to leach the copper. At the cathode, H2 is obtained ( in place of Na ). Example : In refining of Cu At anode : (oxidation) In this method, impure zinc becomes the anode while the cathode is a pure copper strip. (iii) Role of cryolite in the metallurgy of aluminium. Question 74. Kontakt Amsterdamer Str. This is called the anode mud. (i) Zone refining (i) Pig iron into steel. Delhi 2012) Answer: Answer: Mineral: The naturally occuring chemical substances in form of which the metals occur in the earth along with impurities are called minerals. Q11. (ii) Nickel is heated in a stream of carbon monoxide forming a volatile complex, nickel tetracarbonyl which is further subjected to higher temperature so that it is decomposed to give pure nickel. Name the processes from which chlorine is obtained as a by-product. (ii) Vapour phase refining (All India 2013) (i) Electrolytic refining of metals Your email address will not be published. Question 57. Q21. (ii) Electrolytic refining of metals: Here the impure metal is made to act as anode and a strip of the same metal in pure form is used as cathode. Auf der Grundlage der vom 11. bis 31. However, the Gibbs free energy of formation of CO2 from CO is greater than the Gibbs free energy of formation of ZnO. Accessori e mangimi per animali, blog di animali Wenn die Augen brennen und jucken:Trockenheit kann viele Ursachen haben. (All India 2016) 2Na [ Al ( OH)4 ](aq) + CO2 ⇒ Al2O3.xH2O(s) + 2NaHCO3(aq)hydrated alumina (ii) Cryolite in the extraction of aluminium from pure alumina. Answer: (i) using collectors. (All India 2016) (i) To selectively prevent the formation of froth by one of the sulphide ore present in a mixture of sulphide ores. Af cathode : (reduction) Froth floatation method : This method is used for removing gangue from sulphide ores. The powdered bauxite ore is heated with cone. Answer: (iii) The iodine is used in refining of zirconium to form a volatile iodide which on decomposition at high temperature gives pure metal. Mond process for refining of nickel : Question 21. (d) Converted into a chloro complex of Hg Oxidation involves [NCERT 1971, 81; CPMT 1980, 82, 83; 18. Question 16. (i) Mond process (ii) van Arkel method Question 42. Answer: (i) Name the method of refining to obtain silicon of high purity. Separation of alumina from silica in bauxite ore associated with silica is as follows : Thus, in hydro-metallurgy iron and zinc can be used to displace copper from its solution.Fe(s) + Cu2+(aq) ⇒ Fe2+ (aq) + Cu(s) Copper pyrites What is the composition of ‘Copper matte’? Januar 2021 gültigen Coronaschutzverordnung NRW, §6 (4) … Define the following terms: This method is very useful for producing metals of very high purity Example : germanium, gallium etc. With in-depth features, Expatica brings the international community closer together. Question 53. Copper matte chiefly consists of Cuprous Sulphide (Cu2S) and some uncharged Ferrous Sulphide (FeS). All India 2012) (a) Zone refining of metals: This method is based on the principle that impurities are more soluble in the molten state of the metal (the melt) than in the solid state. Question 77. (i) Mond’s Process use in the refining of nickel (ii)The melting point of alumina is very high. The electrolyte is a salt solution of the same metal. (ii) The bauxite ore is treated with sodium hydroxide solution. All India 2014) All India 2012) Why is zinc not extracted from zinc oxide through reduction using CO? Name an element which is refined by this method. 1. (Comptt. Question 35. (ii) Vapour phase refining of metals : Flere the impure metal is converted into its volatile compound and collected elsewhere which is then decomposed by heating at a higher temperature to give pure metal. Maler HEYSE: Malerarbeiten, Fussboden, Fassaden, WDVS-Wärmeschutz, Sanierung, Hannover. (b) How is wrought iron different from steel? (i) The role of cryolite (Na3AlF6) is to lower the melting point of the mixture and bring conductivity. Herzlich Willkommen im Shop von Cashkurs. Answer: (ii) To remove impurity FeO in the form of slag (FeSiO3) This way the different components of the mixture are separated as they move through the stationary phase. As a result, pure metal crystallizes out of the melt and the impurities pass to the adjacent molten zone. Silicon, boron, , gallium etc. In zone refining, a moving circular heater slowly moves over an impure metal rod/ bar. All India 2012) Answer: Role : Collectors e.g. (ii) Froth floatation method of concentration of a sulphide (All India 2011) (i) Hydraulic washing The metals having low boiling points (Bi, Hg, Cd etc.) Delhi 2013) Answer: Zone refining: It is based on the principle that the impurities are more soluble in molten state than in the solid state of the metal. After filteration of impurities sod. In the process of zone refining, a circular mobile heater is fixed at one end of a rod of impure metal. Describe the principle involved in each of the following processes : Answer: (Comptt. When they both are put in suitable electrolyte containing soluble salt of same metal, the more basic metal remains in the solution and the less basic ones go to the anode mud. In this powdered ore is mixed with collectors (e.g. To master Class 12 chemistry one must solve the NCERT questions provided at the end of each chapter. (ii) Leaching of Alumina or Bayer’s process. 2CU2S + 3O2 → 2CU2O + 2SO2 This is a very useful method of purifying elements present in minute amounts. and froth stabilisers (e.g. Question 1. This phase ( stationary ) is immiscible and immobile. Write the principle of the following: (ii) During roasting copper pyrites are converted into a mixture of FeO and CuzO. Question 81. (a) Zone refining: Predict conditions under which Al might be expected to reduce MgO. Answer: Describe the following : (i) During roasting copper pyrites are converted into a mixture of FeO and Cu2O. Answer: (iii) Limestone decomposes in the blast fumance into CaO and CO2 where CaO acts as basic flux which combines with acidic impurities of the ore like silica i.e., SiO2 to form calcium silicate in the form of slag. Silica (SiO2) present as lining acts as flux and combines with FeO to form slag. Cast iron is made by melting pig iron and coke with the help of a hot air blast. What is the role of NaOH in the metallurgy of aluminium? It can also be used for testing the purity of a compound. All India 2014) What is the role of collectors in this process? Explain the role of each of the following in the extraction of metals from their ores : (ii) Zinc oxide into metallic zinc. Answer: There are numerous chromatographic techniques like column chromatography, paper chromatography, gas chromatography, etc. (ii) Germanium: Zone refining. (iv) Froth stab ilisers decrease wettability of gangue. NCERT Chemistry Class 12 solutions chapter 6 has answers to textbook questions along with exemplary questions and class 12 chemistry chapter 6 important questions from previous year question papers. Question 66. (ii) During roasting copper pyrites are converted into a mixture of FeO and Cu2O. (iii) Impure titanium into pure titanium (By Van Arkel method) : The impure titanium is heated in an evacuated vessel with iodine at 870 K. The covalent volatile titanium tetraiodide thus formed is separated which is then decomposed by heating over a tungsten filament at 2075 K to give pure titanium. FeO +C → Fe + CO (i) Name the method of refining of nickel. Although thermodynamically feasible, in practice, magnesium metal is not used for reduction of Alumina in the metallurgy of aluminium. 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