Below are the reduction reactions for oxygen and the P680 ½/20₂ +2 e + 2 H+ → H₂O E = 0.82 V P680* + 1 e → E = 1.15 V P680 What is the potential for the reduction of P680* by water? What is the AG" for the reduction of P680* by water? The oxidation of one molecule of water results in the pumping of two protons. If the AG" for each proton pumped across the thylakoid membrane is +20 kJ/mol, what percentage of the energy from water oxidation is stored in the proton gradient? 2. of photosystem II.

Below are the reduction reactions for oxygen and the P680 ½/20₂ +2 e + 2 H+ → H₂O E = 0.82 V P680* + 1 e → E = 1.15 V P680 What is the potential for the reduction of P680* by water? What is the AG" for the reduction of P680* by water? The oxidation of one molecule of water results in the pumping of two protons. If the AG" for each proton pumped across the thylakoid membrane is +20 kJ/mol, what percentage of the energy from water oxidation is stored in the proton gradient? 2. of photosystem II.

Chemistry: Principles and Practice

3rd Edition

ISBN:9780534420123

Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer

Publisher:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer

Chapter18: Electrochemistry

Section: Chapter Questions

Problem 18.44QE: For each of the reactions, calculate E from the table of standard potentials, and state whether the...

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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-.
Consider a voltaic cell in which the following reaction occurs. Zn(s)+Sn2+(aq)Zn2+(aq)+Sn(s) (a) Calculate E° for the cell. (b) When the cell operates, what happens to the concentration of Zn2+? The concentration of Sn2+? (c) When the cell voltage drops to zero, what is the ratio of the concentration of Zn2+ to that of Sn2+? (d) If the concentration of both cations is 1.0 M originally, what are the concentrations when the voltage drops to zero?
The saturated calomel electrode. abbreviated SCE. is often used as a reference electrode in making electrochemica1 measurements. The SCE is composed of mercury in contact with a saturated solution of calomel (Hg2Cl2). The electrolyte solution is saturated KCI. is +0.242 V relative to the standard hydrogen electrode. Calculate the potential for each of the following galvanic cells containing a saturated calomel electrode and the given half-cell components at standard conditions. In each case. indicate whether the SCE is the cathode or the anode. Standard reduction potentials are found in Table 17.1. a. Cu2++2eCu b. Fe3++e-Fe2+ c. AgCl+e-Ag+Cl- d. Al3++3eAl e. Ni2++2eNi
Calculate the theoretical potential of each of the following cells. Is the cell reaction spontaneous as written or spontaneous in the opposite direction? (a) Pt|Cr3+(2.00 10-4M),Cr2+(1.50 10-3 M)||Pb2+ (5.60 0215 10-2M)|Pb (b) Hg|Hg22+(2.00 10-2 M)||H+(1.50 10-2 M),V3+ (2.00 10-2M),VO2+(3.00 10-3M)|Pt (e) Pt|Fe3+(3.00 10-2 M), Fe2+ (4.00 10-5M)||Sn2+ (3.50 10-2M), Sn4+ (5.50 10-4 M)|Pt
For each of the reactions, calculate E from the table of standard potentials, and state whether the reaction is spontaneous as written or spontaneous in the reverse direction under standard conditions. (a) Zn(s)+Fe2+(aq)Zn2+(aq)+Fe(s) (b) AgCl(s)+Fe2+(aq)Ag(s)+Fe3+(aq)+Cl(aq) (c) Br2(l)+2Cl(aq)Cl2(g)+2Br(aq)
For each of the following reactions, determine the overall balanced electrochemical reaction, its standard electric potential, and the standard Gibbs energy of the reaction. aCo+F2Co2++2F bZn+Fe2+Zn2++Fe c Zn+Fe3+Zn2++Fe d Hg2++HgHg22+
At 298 K, the solubility product constant for PbC2O4 is 8.5 1010, and the standard reduction potential of the Pb2+(aq) to Pb(s) is 0.126 V. (a) Find the standard potential of the half-reaction PbC2O4(s)+2ePb(s)+C2O42(aq) (Hint: The desired half-reaction is the sum of the equations for the solubility product and the reduction of Pb2+. Find G for these two reactions and add them to find G for their sum. Convert the G to the potential of the desired half-reaction.) (b) Calculate the potential of the Pb/PbC2O4 electrode in a 0.025 M solution of Na2C2O4.
Consider a concentration cell that has both electrodes made of some metal M. Solution A in one compartment of the cell contains 1.0 M M2+. Solution B in the other cell compartment has a volume of 1.00 L. At the beginning of the experiment 0.0100 mole of M(NO3)2 and 0.0100 mole of Na2SO4 are dissolved in solution B (ignore volume changes), where the reaction M2+(aq)+SO42(aq)MSO4(s) occurs. For this reaction equilibrium is rapidly established, whereupon the cell potential is found to be 0.44 V at 25C. Assume that the process M2++2eM has a standard reduction potential of 0.31 V and that no other redox process occurs in the cell. Calculate the value of Ksp for MSO4(s) at 25C.
The half-cells Ag+(aq. 1.0 M)|Ag(s) and H+(aq, ? M)|H2(1.0 bar) are linked by a salt bridge to create a voltaic cell. With the silver electrode as the cathode, a value of 0.902 V is recorded tor kcell at 298 K. Determine the concentration of H+ and the pH of the solution.