CHM 320 - Lecture 25 Chapt 14Standard PotentialsChapter 14 continued• Standardized potentials (Eo), listed as reductions, for all half-reactions• Measured versus the S.H.E (0)• Used in predicting the action in either a galvanic cell or how much energy would be needed to force a specific reaction in a non-spontaneous cell• Assumes an activity of one for the species of interest (usually a fair approximation) at a known temperature in a cell with the S.H.E.• Assumes that the cell of interest is connected to the (+) terminal of the potentiometer (voltmeter) and the S.H.E. is connected to the (-) terminalCHM 320 - Lecture 25 Chapt 14Better Oxidizing Agents in upper left hand corner.Better ReducingAgents in lowerRight hand cornerCHM 320 - Lecture 25 Chapt 14What is E°’??• E°’ is used in biochemistry to express the standard reduction potentials (E°) for conditions at pH 7.• E°’ is more useful for biochemists since most biological systems are near pH 7.• Many redox reactions involved H+-- by expressing E° as E°’, then it is understood that the [H+] = 10-7M. • Table 14-2 (pg. 303) lists the E° and E°’for various reduction reactions of interest in biochemistry.CHM 320 - Lecture 25 Chapt 14Using the Nernst Equation to Solve for a Species Concentration(Chemical Sensor)The cell is described as follows. Solve for the concentration of chloride if the measured cell voltage is 0.485 V(s)(s)?M) (aq,-3.6) pH (aq,atm) 1.00 (g,2(s)Ag |AgCl | Cl IIH | H | Pt=+CHM 320 - Lecture 25 Chapt 14Problem - Calculate the Ecellfor the following:Fe(s) ⏐FeBr2(0.010M) ⏐⏐ NaBr (0.050 M) ⏐ Br2(l) ⏐ Pt(s)CHM 320 - Lecture 25 Chapt 14Problem - A mercury cell used to power pacemakers runs on the following reaction:Zn(s)+ HgO(s)= ZnO(s)+ Hg(l)E° = 1.35 VIf the power required to operate the pacemaker is 0.0100 W, how many kilograms of HgO (FM 216.59) will be consumed in 365 days? How many pounds of HgO is this (1 lb = 453.6 g)?Applications of electrochemistry in analytical