InterviewSolution
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InterviewSolution
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A voltaice cell constructed form two half-cells composed of the same material but differing in ion concentration is calledA. a chemical cellB. a concentration cellC. electrolytic cellD. an electrochemical cell. |
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Answer» Correct Answer - B Any galvanic cell in which two half-cell reactions use different reactants is called a chemical cell. Deniell cell is one such example. If the chemical reactions in two half-cells are the same, the concentrations of the ionic species are different, then the net result is the transfer of species form higher concentration to lower concentration. There is no net chemical reaction in the cell. Such cells are commmonly known as concentration cells For example, `{:(" "Zn(s)|ZnSO_(4)(C_(1))||ZnSO_(4)(C_(2))|Zn(s)),("Anode":" "Zn(s) hArr Zn^(2+)(C_(1))+2e^(-)),("Cathode" :Zn^(2+)(C_(2))+2e^(-)hArrZn(s)),(bar("Cell reaction :"Zn^(2+)(C_(2))hArr Zn^(2+)(C_(1)))):}` At `298 K` `E_("cell") = E_("cell")^(@) - (0.0592 V)/(2) log (C_(1))/(C_(2))` Since `E_("cell")^(@)` for a concentration cell is zero because the same electrodes and the same type of ions are involved, we have in general `E_("cell") = (0.0592 V)/(n) "log" (C_(2))/(C_(1))` Note that for the process to be feasible, `E_("cell")` should the posi-tive i.e. `C_(2) gt C_(1)`. |
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