Why in concentration cells standard electrode potential is 0 are of the samne material the concentration

ELECTROCHEMISTRY 22. Concentration Cells VOLTMETER Concentration cells are the cells in which her the two electrodes are of the samne material the concentration of the electrolyte in them iferent pr the two electrodes have diferent CURRENT roH noiuloe ZINC ELECTRODE g1 1centration but they are immersed in the same tion of the electrolyte. The former are called ELECTRODE y. ctrolyte concentration cells while the latter called electrode concentration cells. ZINC ZnSO4 SOL (CONC C1) The most common concentration cell is the trolyte concentration cells. For example, H,IHC)1IH(C)IH and Zn Zn2 (C)|1Zn2 (C,) 1 Zn ZnSO4 SOL (CONC = C2) C2>C1 POROUS PARTITION One such cell consisting of zinc electrodes Concentration cell consisting of zinc electrodes +3 NiOwn in Fig. 3.19. The EMF of a concentration cell at 298 K is given by ta (an)HT4 0-0591 Ecell 108 27045 n Obviously, EMF of the cell will be positive only if C, >E n such a cell, oxidation takes place on the electrode with lower concentration. Hence, it acts as e (or-ve pole). The reduction takes place on the electrode with higher concentration which, therefore, cathode (or +ve pole). For example, in the concentration cell consisting of zinc electrodes, the Dde reactons will be Zn (s) Zn* (C) +2e Zn () 9 V. Zn2 (C,)+2e Overall reaction Zn2C) Zn(C) nere is no net chemical reaction. It simply involves transfer of electrolyte from one concentration other Pplying Nernst equation, at 298 K 0-0591 0-0591 log log 080 Eeell C n rther 059 e cell reaction proceeds, C, decreases whereas C increass till the two become equal, i.e At this stage, Ecell Shmlarly, ina ode co cell 0 and hence the cell stops working.7 a concentration cell of the type Pt, H, (Pj atm) I H (conc. = C) I H, (P, atm), Pt (called tration cell) in which the two electrodes are immersed in the same solution but have Sures or concentrations, cell 0-0591 log P> P). blem1 Calculate the EMF of the fai