10 Mg(s) + Cd(aq) -> Mg (aq) + Cd(s) E = +1.98 V The magnesium electrode was dipped into a 1.00 M salution of M9SO4 and the cadmium elestrede was dipped into a solution of unknown Cd* concentration. The pctential of the cell was measured to be +1.54 V. What was the unknown Cd? concentration? (Answer: 1.4 x 1015 M)

10 Mg(s) + Cd(aq) -> Mg (aq) + Cd(s) E = +1.98 V The magnesium electrode was dipped into a 1.00 M salution of M9SO4 and the cadmium elestrede was dipped into a solution of unknown Cd* concentration. The pctential of the cell was measured to be +1.54 V. What was the unknown Cd? concentration? (Answer: 1.4 x 1015 M)

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter24: Coulometry

Section: Chapter Questions

Problem 24.5QAP: What cathode potential (versus SCE) would be required to lower the total Hg(II) concentration of the...

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The following cell was found to have a potential of —0.492 V: Ag|AgCl(sat’d)||HA(0.200 M),NaA(0.300 M)|H2(1.00 atm),Pt Calculate the dissociation constant of HA, neglecting the junction potential.
Halide ions can he deposited at a silver anode, the reaction being Ag(s) + X- AgX(s) +e- Suppose that a cell was formed by immersing a silver anode in an analyte solution that was 0.0250 M Cl-,Br-, and I -ions and connecting the half-cell to a saturated calomel cathode via a salt bridge. (a) Which halide would form first and at what potential? Is the cell galvanic or electrolytic? (b) Could I- and Br- be separated quantitatively? (Take 1.00 l0-5 M as the criterion for quantitative removal of an ion.) If a separation is feasible, what range of cell potential could he used? (c) Repeat part (b) for I- and Cl-. (d) Repeat part (b) for Br- and Cl-.
The cell Ag|AgCl(sat’d)||H+(a = x)|glass electrode has a potential of —0.2094 V when the solution in the right-hand compartment is a buffer of pH 4.006. The following potentials are obtained when the buffer is replaced with unknowns: (a) —0.2806 V and (b) —0.2132 V. Calculate the pH and the hydrogen ion activity of each unknown. (c) Assuming anuncertainty of 0.001 Vin the junction potential, what is the range of hydrogen ion activities withinwhich the true value might be expected to lie?
What cathode potential (versus SCE) would be required to lower the total Hg(II) concentration of the following solutions to 1.00 10-6 M (assume reaction product in each case is elemental Hg): (a) an aqueous solution of Hg2+? (b) a solution with an equilibrium SCN- concentration of 0.100 M? Hg2+ + 2SCN- Hg(SCN)2(aq) = Kf = 1.8 107 c) a solution with an equilibrium Br- concentration of 0.100 M? HgBr42++ 2e- Hg(l) + 4Br- E0= 0.223 V
The following cell was found to have a potential of 0.124 V: Ag|AgCl(sat’d)||Cu2+ (3.25 10-3 M|mernbrane electrode for Cu2+ When the solution of known copper activity was replaced with an unknown solution, the potential was found to be 0.055 V. What was the pCu of this unknown solution? Neglect the junction potential.