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InterviewSolution
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How is ozone prepared? How does it react with the following? (i) PbS (ii) KI (iii) Hg (iv) Ag |
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Answer» Preparation of Ozone : A slow dry stream of oxygen under silent electric discharge to form ozone (about 10%). The product obtained is known as ozonised oxygen. 3O2 → 2O3 ∆H° = 142kJ/mole → The formation of ozone is an endothermic reaction. → It is necessary to use silent electric discharge in the preparation of O3 to prevent its de- composition (i) Reaction with PbS : Black lead sulphide oxidised to white lead sulphate in presence of ozone. PbS + 4O3 → PbSO4 + 4O2 (ii) Reaction with KI : Moist KI is oxidised to Iodine in presence of ozone. 2KI + H2O + O3 → 2KOH + I2 + O2 (iii) Reaction with Hg : Mercury loses it's lustreness, meniscus and consequently sticks to the walls of glass vessel when it reacts with ozone. This phenomenon is called tailing of mercury. 2Hg + O3 → Hg2O + O2 It is removed by shaking it with water which dissolves Hg2O. (iv)Reaction with Ag : Ag metal oxidised to Ag2O (Ag metal is tarnished). 2Ag + O3 → Ag2O + O2 |
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