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InterviewSolution
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Tarnished silver contains Ag2S. Can this tarnish be removed by placing the tarnished ware in an aluminium pan containing an inert electrolyte solution such as NaCl ? Given that the standard reduction potentials for the half reactions are : `Ag2S(s)+2e^(-)to2Ag(s),+S^(2)(aq), E^(@)=-0.71" V"`. `Al^(3+)(aq)+3e^(-) to Al(s), E^(@)=-1.66" V"`. |
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Answer» Yes, the tarnish due to silver sulphate will be removed by placing the tarnished ware in an aluminium pan. Actually, aluminium is is a stronger reducing agent than silver. Therefore, it will reduce silver ions `(Ag^(+))` to metallic silver. It being silvery white in colour will get slowly deposited on the walls of the silver ware and the tarnish will be removed. `Al(s) +3Ag^(+)(aq) to Al^(3+)(aq)+3Ag(s)` Alternatively, `E_(cell)^(@)=E_(cathode)^(@)-E_(anode)^(@)=(-0.71)-(-1.66)=0.95" V"` is positive. The redox reaction is feasible and the tarnish will be removed. |
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