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Predict whether zinc and silver react with 1 M suphuric acid to give out hydrogen or not given that h standard potentials of zinc and silver are -0.76 vold and +0.80 volt respectively |
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Answer» Solution :(a) To predict reaction of zinc with suphuric acid in Zn reacts the following reaction shuld take place `Zn+H_(2)SO_(4)rarrZnSO_(4)+H_(2) i.e Zn+2H^(+)rarrZn^(2+)+H_(2)` By convention the cell MAY be represented as `Zn|zn^(2+)||H^(+)|H_(2)` standart EMF of the cell `E_(cell)^(@)=(H)^(+)/(H_(2))^(E^(@))(Zn^(2+)//Zn)=0-(-0.76)` Thus the EMF of tthe cell comes bout to be positive HENCE the reaction takes place (b)To Predict the reaction of silver with suplhuric acid If Ag rects the following reactionshuld take lace `2Ag+H_(2)SO_(4) RARR Ag_(2)SO_(4)+H_(2) i.e 2Ag+2H^(+) rarr2Ag^(+)+H_(2)` By convention the cell may be represented as `As|Ag^(+)||H^(+)|H_(2)` Thus the EMF of the supposed acell comes out to be negatvie hence this reaction does not take place agent than `H_(2)` and hence can reduce `H^(+)` IONS to evolve `H_(2)` GAS in contrast since `E_(H^(+)//GH_(2)^(@)` =0.0 V therefore Zn is a stronger reducigng that of `E_(H^(+)//H_(2))^(@)=0.0V`therefore Ag is a weaker reducing agent than `H_(2)` and hence cannot reduce `H^(+)` ions ot evolve `H_(2)` gas |
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