Question

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Reference Electrodes The Eº value for the following reaction is 0.446 V relative to the standard hydrogen electrode (SHE): AgzCrO4(s) + 2e + 2Ag(s) + Cro 2(aq) A chemist wishes to determine the concentration of Cro42 electrochemically. A cell is constructed consisting of a saturated calomel electrode (SCE; which has a reduction potential of 0.242 V relative to the SHE) and a silver wire coated with Ag CrO4 and suspended in a Cro42-solution. What is the potential of this cell at 25°C when [Cro42-) = 1.00 M? 1 pts Submit Answer Tries 0/5 Calculate AG for the full-cell reaction at 25°C when (CrO42-) = 1.00 M? 1pts Submit Answer Tries 0/5 What is the potential of this cell at 25°C when (CrO42-) = 2.60x10- M? 1 pts Submit Answer Tries 0/5 For a solution of unknown (CrO42-], the measured potential for the cell at 25°C is 0.540 V. What is CrO42-1 (in mol/L)? Opts Submit Answer Tries 0/5

Answer 1

Can Given cell Reaction Ag,croq (s1 & 26 2 Agisl + crop lag E = stand and Reduction potential for Half cell = Esce = o. 242 volt 0.446 volt Eren = standard Reduction potential for cell =(0.446-0.242) v. = 0. 2040 Applying Mennst equation - Capgest & [croz] Ecell = Ecey - 2.3058 Tog Acrosis RR = 8.3 14J/kl mole T=298k I = 96500c/mole n = No of election Lost / gained TX 1.oom Ecoll = Ecell -..osg log | 1000 Ecel = 0.24 volt ! Anower Ecell a cell potential - [cro, 2-] = loom Activity of pure solide and liquide is taken as Zero AG = Gibbs free Energy change AGO = standard Gibbs free Energy change AG = AGO + o = Reaction Ring Quotient (@Agisi) 2 *[ croq? -] a rust = AG - AG = nFe cell & Ribs - -a mole & 965oocanule x - 39.372 kJ] Ans 0.2040 [oolks = 10005]

0 [cro2 = 2.60*108M Ecce = Focu - oooss log , T = 298k anges ² x crop 2 - 1 OAB. Creast 1 x = 2.60X - 0. zoavelt - oss log ("* 2.60x1en) I 0.204 volt -0.059 log = 0.4277 volt = E cell = Feet = (0.204 +0.2237)volt et vot Anowan 0.4277 Volt D L = E cell = 0.540 volt Given cell potential Eceep = 0.204 volt T = 298K Ecel = Ezek - 0.059 log ( 43 ) 0.540 = 0.2 04Volt - 0.059 fogl crepe Jx). 0.059 ton [ro]) = -0.336 log[[croz-1) = - 11:389 Taking Antilog both sides we get, [cool] =10 4-11-389

Гcto42-1 = 4.0 x 10' M TAngо е