InterviewSolution
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InterviewSolution
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An electrochemical cell is constructed with an open switch as shown below: when the switch is closed, mass of tin-electrode increases. If `E^(@) (Sn^(2+)//Sn) = 0.14V` and for `E^(@) (X^(n+)//X) =- 0.78V` and initial emf of the cell is `0.65V`, determine n and indicate the direction of electron flow in the external circuit. |
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Answer» Correct Answer - `n = 3 & X`-electrode to Sn-electrode At cathode: `Sn^(+2) +2e^(-) rarr Sn` At anode: `X rarr X^(+n) +n e^(-)` Cell reaction `nSn^(+2) +2X rarr 2X^(+n) +nSn` `E^(@) =- 0.14 +0.78 = 0.64` `E = E^(@) -(0.0591)/(2n)log.([X^(+n)]^(2))/([S^(+2)]^(n))` `0.65 =0.64 -(0.0591)/(2n) [log 0.01 -log (0.5)^(n)]` `0.01 =- (0.0591)/(2n) [-2 +n log 2]` `0.03384 n = 2 -0.3010n` `0.6394 n = 2` `n = 3.12 =3` |
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