General Principles & Processes of Isolating Elemen
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New answer posted
4 months agoContributor-Level 10
Above 1350oC, the standard Gibbs free energy formation of Al2O3 from Al is less than that of MgO from Mg. Therefore, above 1350oC, Al can reduce MgO.
New answer posted
4 months agoContributor-Level 10
(i) Zone refining Is the method based on the principle that the impurities are more soluble in the melt than in the solid state of the metal.
(ii) Electrolytic refining works on the principle of refining impure metals by the use of electricity. In Electrolytic refining, the impure metal is made the anode and a strip of pure metal is made as the A solution of a soluble salt of the same metal is taken as the electrolyte. When an electric current is passed, metal ions from the electrolyte are deposited at the cathode as a pure metal and the impure metal from the anode dissolves into the electrolyte in the form of ions. The impurities pre
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4 months agoContributor-Level 10
Graphite rod acts as anode and graphite lined iron acts as a cathode in the electrometallurgy of aluminium. Carbon reacts with oxygen liberated at anode producing CO and CO2 otherwise oxygen liberated at the anode may oxidize some of the liberated aluminium back to Al2O3.
New answer posted
4 months agoContributor-Level 10
In the electrolysis of NaCl by Down's process, chlorine is obtained as a by-product. This process involves the electrolysis of a fused mixture of NaCl and CaCl2 at 873K. during electrolysis, sodium is liberated at the cathode and Cl2 is liberated at the anode.
If an aqueous solution of NaCl is electrolysed, H2 is evolved at the cathode and Cl2 is obtained at the anode, the reason being that E0 of Na+/Na redox couple is much lower (E0 = - 2.71 V) than that of H2O (EH2O/H20 = - 0.83V ) and hence water is reduced to H in presence of Na+ ions. However, NaOH is obtained in the solution.
New answer posted
4 months ago
Contributor-Level 10
Thermodynamic factors help us in choosing a suitable reducing agent for the reduction of a particular metal state as described below.
From Ellingham diagram, it is evident that metals for which the standard free energy of formation of their oxides is more negative can reduce those metal oxides for which the standard free energy of formation of their respective oxides is less negative. In other words, any metal will reduce the oxides of other metals which lie above in the Ellingham Diagram because the standard free energy change of the combined redox reaction will be negative by any amount of equal to the difference in Δ fG0 of the two
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4 months agoContributor-Level 10
The free energy formation ( ΔfGo ) of CO from C becomes lower at temperatures above 1120K whereas that of CO2 from C becomes lower above 1323K than ΔfG0 of ZnO. However, Δ fG0 of CO2 from CO is always higher than that of ZnO. Therefore, C can reduce ZnO to Zn but not CO. therefore, out of C and CO, C is a better reducing agent than CO for ZnO.
New answer posted
4 months agoContributor-Level 10
The value of Δ fG0 for the formation of Cr2O3 is – 540 kJ mol-1 which are higher than that of Al2O3 is – 827 Kjmol-1. Thus, Al can reduce Cr2O3 to Cr. Hence, the reduction of Cr2O3 with Al is possible.
New answer posted
4 months agoContributor-Level 10
The standard Gibbs free energy formation of ZnO from Zn is lower than that of CO2 from CO. That is why CO cannot reduce ZnO to Zn. thus, Zn is not extracted from ZnO through reduction using CO.
New answer posted
4 months agoContributor-Level 10
For the group of low-grade copper ores, leaching is carried out using acid or bacteria in the presence of air or oxygen. In this process, copper goes into the solution as Cu2+ ions.
The resulting solution is then treated with scrap iron or H2 to obtain metallic copper.
New answer posted
4 months agoContributor-Level 10
Cryolite (Na3AlF6) has two roles in the metallurgy of aluminium:
(i) It lowers the melting point of the mixture to about
(ii) It increases the electrical conductivity of the
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