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Kohlrausch's law of indendent migration of ions states that the molar conductance of infinite dilution (limiting molar conductivity ) is the sum of the individual contributions of the anions and cations of the electrolyte. It can be given in the mathematical form as: λ 0 M = v + λ 0 + + v - λ 0 - λ 0 + and λ 0 - are the limiting molar conductivity of cation and anion respectively. For NaCl, λ 0 M = λ 0 Na+ + λ 0 Cl- And for Al2(SO4)3, λ 0 Al2(SO4)3 =2 λ 0 Al3+ + λ 0 SO4 2-

In the laboratory phosphine is prepared by heating white phosphorus with concentrated caustic alkali solution in an inert atmosphere of oil gas or CO2. P4 + 3NaOH + 3H2O ------------> 3NaH2PO2 (Sodium hypophosphite) + PH3 (phosphine) Metal phosphides on hydrolysis form phosphine Ca3P2 + 6H2O ------------> 3Ca(OH)2 + 2PH3 A pure sample of phosphine can also be prepared by heating phosphorous acid 4H3PO3 ---------------> 3H3PO4 + PH3 Phosphine has pyramidal structure and is a weaker base than NH3

The main oxides of phosphorus are phosphorus trioxide (P4O6) and phosphorus pentoxide (P4O10) . Phosphorous trioxide is regarded as the anhydride of phosphorous acid (H3PO4). phosphorus trioxide (P4O6) is prepared by heating phosphorous in limited supply of oxygen. P4O10 is prepared by burning white phosphorous in excess of air or oxygen. P4 + 3O2 -------------> P4O6 P4 + 5 O2 ------------> P4O10 P4O10 has great affinity for water and hence it is used as a dehydrating agent. It can dehydrate HNO3 and H2SO4 to yield N2O5 and SO3 respectively. 2H2SO4 + P4O10 ------------> 2SO3 + 4HPO3 P4O6 and P4O10 dissolves in water to give phosphorus acid and orthophosphoric acid respectively. P4O6 + 6H2O -------------> 4H3PO3 P4O10 + 6H2O --------------> 4H3PO4 Related article oxyacids of phosphorus

Sulphur occurs in nature in the elemental forms, as metal sulphides and as sulphates. Sulphur also occurs as H2S present in natural gas. Sulphur is extracted by the following methods 1. Frasch process In this process, sulphur is extracted from underground deposits by pumping super heated steam down the beds to melt the sulphur and then blown out the molten sulphur with compressed air. 2. Extraction of sulphur from natural gas Natural gas contains a large amount of hydrogen sulphides (H2S). Hydrogen sulphide is first absorbed in monomethanolamine and then converts H2S into sulphur by the following reactions. 2H2S + 3O2 ------------> 2SO2 + 2H2O 2H2S + SO2 ------------> 3/8 S8 + 2H2O (at 673K and Fe2O3 as catalyst) Related article extraction of aluminium extraction of copper

Xenon trioxide (XeO3) XeO3 prepared by the slow hydrolysis of XeF6 XeF6 + 3H2O ------------> XeO3 + 6HF Xenon trioxide is soluble in water and its aqueous solution is weakly acidic. XeO3 + H2O <--------> H+ + HXeO4 – Xenate ion XeO3 has pyramidal structrure in which Xe is in sp3 hybridisation. Xenon tetroxide (XeO4) It is prepared by treating barium perxenate (Ba2XeO6) with anhydrous sulphuric acid. Ba2XeO6 + 2H2SO4 -----------> XeO4 + 2BaSO4 + 2H2O Xenon tetroxide is highly unstable and has tetrahedral structure. Related article fluorides of xenon For more detail visit indiastudychannel.com

Hydrogen sulphide is prepared in laboratory by the action of dilute HCl or dilute H2SO4 on ferrous sulphide in Kipp’s apparatus. FeS + H2SO4 ---------->4 + H2S Physical properties It is colourless gas with the smell of rotten eggs. It is denser than air and is soluble in water. Chemical properties 1. Combustibility Hydrogen sulphide burns in limited supply of oxygen to form sulphur. In presence of excess of oxygen, it gives sulphur dioxide. 2. Acidic property H2S is a weak dibasic acid and forms two types of salts namely bisulphides and sulphides NaOH + H2S ----------> NaHS + H2O 2NaOH + H2S ----------> Na2S + 2H2O 3. Action with metals When H2S is passed over hot metals the sulphides and hydrogen are formed Cu + H2S -----------> CuS + H2 4. Hydrogen sulphide in qualitative analysis H2S precipitates metal sulphides having characteristic colours from metal salt solutions in acidic or alkaline medium. Therefore H2S is used in qualitative analysis to identify metal ions belong...