• # question_answer   Is it possible to store: (i) Copper sulphate solution in a zinc vessel? (ii) Copper sulphate solution in a silver vessel? (iii) Copper sulphate solution in a gold vessel? Given: $E{{{}^\circ }_{C{{u}^{2+}},\,Cu}}=+0.34\,V;$$E{{{}^\circ }_{A{{g}^{+}},\,Ag}}=+0.80\,V$ and$E{}^\circ {{\,}_{A{{u}^{3+}},\,Au}}=+\,1.50\,V$.

(i) We cannot place $CuS{{O}_{4}}$ solution in a zinc vessel, if the following redox reaction occurs: $Zn+CuS{{O}_{4}}\xrightarrow{{}}\,ZnS{{O}_{4}}+Cu$ or$Zn+C{{u}^{2+}}\xrightarrow{\,}\,Z{{n}^{2+}}+Cu$ By convention, the cell may be represented as $Zn|Z{{n}^{2+}}||C{{u}^{2+}}|Cu$ $\therefore$  $E{{{}^\circ }_{cell}}=E{{{}^\circ }_{C{{u}^{2+}},Cu}}-E{{{}^\circ }_{Z{{n}^{2+}},Zn}}$   $=0.34-(-0.76)=+1.10\,V$ Since EMF comes out to be positive, therefore, $CuS{{O}_{4}}$ reacts with zinc. In other words, $CuS{{O}_{4}}$ solution cannot be stored in a zinc vessel. (ii) We cannot store $CuS{{O}_{4}}$ solution in a silver vessel if the following redox reaction occurs: $2\,Ag\,+C{{u}^{2+}}\xrightarrow{\,}\,2\,A{{g}^{+}}\,+Cu$ By convention, the cell of the above redox reaction may be represented as $Ag|A{{g}^{+}}||C{{u}^{2+}}|\,Cu$and$E{}^\circ {{\,}_{cell}}\,=E{{{}^\circ }_{C{{u}^{2+}},\,Cu}}-E{{{}^\circ }_{A{{g}^{+}},\,Ag}}$ $=0.34-0.80=-0.56\,V$ Since the EMF of the cell is ?ve, therefore, $CuS{{O}_{4}}$ does not react with silver. In other words, $CuS{{O}_{4}}$ solution can be stored in a silver vessel. (iii) We cannot store $CuS{{O}_{4}}$ solution in a gold vessel if the following redox reaction occurs: $2\,Au+3\,C{{u}^{2+}}\xrightarrow{\,}\,2\,A{{u}^{3+}}+3\,Cu$ The cell corresponding to the above redox reaction may be represented as $Au|A{{u}^{3+}}||C{{u}^{2+}}|Cu$ and$E{}^\circ {{\,}_{cell}}\,=E{{{}^\circ }_{C{{u}^{2+}},\,Cu}}-E{{{}^\circ }_{A{{u}^{3+}},\,Au}}$$=0.34-1.50=-1.26\,\text{V}$ Since the EMF of the above cell reaction is ? ve, therefore, $CuS{{O}_{4}}$ solution does not react with gold. In other words, $CuS{{O}_{4}}$ solution can be stored in a gold vessel.