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Chemistry Selina Chapter Answers



NOTES (Scroll down for Answers)

Ammonia is basic gas with formula NH3. It is obtained by treating caustic alkali like NaOH , Ca(OH)2 or KOH with Ammonium salts. It is dried by quicklime (CaO) as other agents react with ammonia. It is soluble in water and lighter than air. Aqueous Ammonia is prepared in same way as that of HCl.

          Haber’s process is used to manufature Ammonia. It is a important topic for exams. In this process Nitrogen and Hydrogen are combined in ratio 1 : 3 with finely divided iron as catylst , molybednum or Al2O3  as promoter . It takes place in 450 to 500 degree celcius and between 200 atm to 900 atm.It is exothermic reaction and 15% of Ammonia is yeild. Liquefaction or Aborbtion in water is used to filter residue gases from Ammonia.

          Ammonia is reducing agent and reduce Cl to HCl. It aso reduce metal oxides like CuO and PbO to pure metals. It is combined with Oxygen with platinum as a catylst ; to form NO which gets oxidize to form NO2. It absorbs in water to form NH4OH. It react with HCl or Cl (when ammonia in excess) to give white fumes of Ammonium Chloride.

Ammonia is used in manufacture of urea , dissolving fats and grease, dry cells and explosives.