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Unformatted text preview: Introduction: The objective of this experiment is to determine the transport number and the mobilities of the H+ and Cl- ions. The moving boundary method is used to measure the transport number which is the electric current fraction carried by specific ion. Current = charge / time = charge per ion*number of ions/time number of ions/time = concentration * area * length / time the current carried by ion I is: Ii = F*|Zi|*ci*l*A / t Where l is the average distance the ion move in time t. And A is the area of the tube. We have: T= Ii/I = F* |Zi|*ci*l*A / (t*I) Since: vi = l/t then: Ii = F*|Zi|*ci*A* vi Since the ion velocity is proportional to the electric field: vi = ui E (ui is the ionic mobility) thus: Ii = F*|Zi|*ci*A* ui*E since I = (I+) + (I-) I = [F*|Z + |*(c + )*A* (u + )*E] + [F*|Z-|*(c-)*A* (u-)*E] But |Z+| = |Z-| and also c+ = c- then: T + = I + / (I + )+(I-) = u + / (u + )+(u-) Since the conductivity of the solution is the sum of the ionic conductivity: In this experiment the transport number of the H+ will be determined from the conductivity of the HCl solution and then ionic mobilities u cl- and u H+ will be found....
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- Fall '09