Explain the role of each of the following:
(i) NaCN in the extraction of silver
(ii) SiO2 in the extraction of copper
(i) Name the method of refining of metals such as Germanium.
(ii)In the extraction of Al, impure Al2O3 is dissolved in conc. NaOH to form sodium aluminate and leaving impurities behind. What is the name of this process?
(iii)What is the role of coke in the extraction of iron from its oxides?
(i) Zone refining method is the most suitable method for refining metals like germanium (semiconductor).
(ii) In the extraction of aluminium, impure Al2O3 is dissolved in concentrated NaOH to form NaAlO2.
This method is known as leaching of alumina.
(iii) Coke reduces the iron oxide to molten iron metal. Also, coke, when burnt in the blast furnace, supplies the heat required for carrying out the extraction of iron from its oxide.
FeO +C ---> Fe +CO
Describe the principle controlling each of the following processes:
(i) Preparation of cast iron form pig iron.
(ii) Preparation of pure alumina (Al2O3) from bauxite ore.Explain the principle of the method of electrolytic refining of metals. Give one example.
Out of PbS and PbCO3 (ores of lead), which one is concentrated by froth flotation process preferably?
Write the chemical reactions involved in the process of extraction of Gold. Explain the role of dilute NaCN and Zn in this process