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SILVERING OF MIRROR:
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| To deposit a coating of pure silver on a glass sheet or a glass plate is called silvering of mirror. Silvering process converts a plane glass sheet into a mirror. | |||
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THEORY
OF SILVERING PROCESS
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| Ammonical silver nitrate is a mild oxidizing agent. Its ion, [Ag(NH3)2]+ can oxidize many compounds such as aldehydes and a layer of pure 'Ag' is deposited on the glass surface. In the process Ag+ ions are reduced to Ag metal. | |||
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METHOD
OF SILVERING OF MIRROR
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| (1)
Clear the glass sheet to remove any stain or oily materials. Cleaning is
done with ammonia solution. (2) Prepare aqueous solution of AgNO3. (3) Dilute this solution with ammonium hydroxide solution slowly until brown ppt of silver oxide is redissolved. |
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AgNO3
+ NH4OH è
AgOH + NH4NO3
(white ppt.) AgOH + 2NH4OH è [Ag(NH3)2]OH + 2H2O 2[Ag(NH3)2]OH è Ag2O + H2O + 4NH3 |
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| (4) To this solution add glucose(reducing agent) and immediately pour the solution on the glass sheet to be silvered. It spreads over the surface glass sheet. The reduction begins and 'Ag' is deposited on the glass sheet and a brilliant mirror is formed. www.citycollegiate.com | |||
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| (5) In order to protect the layer of silver, a coating of varnish is deposited over it. | |||
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