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Study Guide for CHEM 102 A, Test 2(DELANEY)

  1. For the reactions below find the equilibrium concentrations of all products and reactants. Assume the initial concentration of all reactants is 2.90 M and the initial concentration of all products is zero (0.00 M).

    1. Mn2(CO)10 + CH3I <------> CH3Mn(CO)5 + IMn(CO)5

      Kc = 1.88 x 10-6

    2. Cl3CCOOH(aq) <------> H+(aq) + Cl3CCOO-(aq)

      Ka = 1.29 x 10-1

  2. Provide the equilibrium expressions for the reactions below:

    1. HCl(aq) + Rh(CO){P(C6H5)3}2Cl(aq) < -----> HRh(CO){P(C6H5)3}2Cl2(aq)

    2. 2 SO2(g) + O2(g) <-----> 2 SO3(g)

    3. HC2H3O2(aq) <-----> H+(aq) + C2H3O2-(aq)

    4. N2O4(g) <-----> 2 NO2(g)

    5. PCl5(g) <-----> PCl3(g) + Cl2(g)

  3. What is the Kc or Kp for the reactions below if the concentrations are those at equilibrium for the reaction?

    1. 2 CO(g) + O2(g) <-----> 2 CO2(g)

      [CO] = 753 torr, [O2] = 325 torr, [CO2] = 1200 torr

    2. HCl(aq) + RhCl3(aq) <------> HRhCl4(aq)

      [HCl] = 6.25 M, [RhCl3] = 1.33 M, [HRhCl4] = 0.0551 M

    3. H2(g) + I2(g) <-----> 2 HI(g)

      [H2] = 0.00926 atm, [I2] = 0.00516 atm, [HI] = 0.00510 atm

  4. What is the equilibrium concentration of the reactant(s) and product(s) in the reactions below given the equilibrium constants and starting concentrations of the reactants?

    1. HCl(aq) + Rh(CO){P(C6H5)3}2Cl(aq) <-----> HRh(CO){P(C6H5)3}2Cl2(aq)

      [HCl] = 1.000 M, [Rh(CO){P(C6H5)3}2Cl] = 1.000 M, Kc = 150.00

    2. HC2H3O2(aq) <:-----> H+(aq) + C2H3O2-(aq)

      [HC2H3O2] = 1.977 M, KA = 1.800 x 10-5

    3. CO(g) + Cl2(g)<:-----> COCl2(g)

      [CO] = 455 torr, [Cl2] = 455 torr, Kp = 1.67 x 10-3

  5. Describe the effects of changing the conditions that chemical a reaction is run under upon the equilibrium of a reaction. Apply LeChatelier's principle using the example given below:

    2 NH3(g) <-------> N2H4(g) + H2(g) the reaction being run in a constant volume vessel

    Which direction would the equilibrium shift if:

    1. the temperature is increased
    2. more NH3 is supplied
    3. more H2(g) is supplied
    4. the N2H4(g) is removed from the system as fast as it is produced
    5. the volume of the reaction vessel is doubled
    6. the volume of the reaction vessel is halved

  6. Calculate Eo for the cells below at standard conditions. Are the cells galvanic (voltaic) or electrolytic?

    1. Zn(s)|Zn2+|sat'd KCl|Fe2+|Fe(s)
    2. Ni(s)|Ni2+|sat'd KCl|Cd2+|Cd(s)
    3. Pb(s)|Pb2+|sat'd KCl|Au3+|Au(s)
    4. Au(s)|Au3+|sat'd KCl|Ag+|Ag(s)
    5. Cr(s)|Cr3+|sat'd KCl|Hg22+|Hg(l)
    6. Al(s)|Al3+|sat'd KCl|Mg2+|Mg(s)
    7. Sn(s)|Sn2+|sat'd KCl|Be2+|Be(s)
    8. Ba(s)|Ba2+|sat'd KCl|Cr3+|Cr(s)
    9. Mn(s)|Mn2+|sat'd KCl|Pb2+|Pb(s)
    10. Cd(s)|Cd2+|sat'd KCl|Zn2+|Zn(s)

  7. Calculate Ecell for the cells below at the non-standard conditions given and 298 K. Are the cells galvanic (voltaic) or electrolytic?

    1. Sn(s)|Sn2+(1.953 M)|sat'd KCl|Zn2+(0.3689 M)|Zn(s)
    2. Hg(l)|Hg22+(1.564 M)|sat'd KCl|Au3+(3.596 M)|Au(s)
    3. Au(s)|Au3+(1.112 M)|sat'd KCl|Ag+(0.7888 M)|Ag(s)
    4. Cu(s)|Cu2+(3.500 M)|sat'd KCl|Ag+(4.000 M)|Ag(s)
    5. Mn(s)|Mn2+(0.7542 M)|sat'd KCl|Sr2+(1.556 M)|Sr(s)
    6. Sn(s)|Sn2+(4.9934 M)|sat'd KCl|Pb2+(0.7848 M)|Pb(s)
    7. Mn(s)|Mn2+(3.000 M)|sat'd KCl|Zn2+(4.000 M)|Zn(s)
    8. Mg(s)|Mg2+(3.984 M)|sat'd KCl|Ni2+(0.8347 M)|Ni(s)
    9. Fe(s)|Fe2+(0.3908 M)|sat'd KCl|Hg22+(2.387 M)|Hg(l)
    10. Ni(s)|Ni2+(3.478 M)|sat'd KCl|Ag+(2.408 M|Ag(s)

  8. What is the Eo for a battery made from aluminum and iodine under standard conditions according to the cell diagram below:

    Al(s)|Al3+(1.00 M)|sat'd KCl |(I2(s)/Pt)|I-(1.00 M)

    What would be the voltage of this cell if the Al3+ concentration is 0.5612 M and the I- concentration is 6.00 M?

  9. Describe the major differences between a "wet cell" (lead-acid battery) and a "dry" cell (carbon-zinc or alkaline battery).

  10. What is the differences between a battery and a fuel cell. What are the advantages and disadvantages of each?

  11. Define:

    1. anode
    2. cathode
    3. oxidizing agent
    4. reducing agent
    5. battery
    6. fuel cell
    7. corrosion
    8. galvanic (voltaic)
    9. electrolytic
    10. cathodic protection
    11. sacrificial electrode or anode

  12. You have a choice of using Mg, Al or Zn as a sacrificial anode for cathodic protection of a piece of iron. You are limited to a volume of 50.00 mL for your sacrificial anode. Which material will you choose and why? (Consider potentials, densities and grams of metal per mole of electrons produced in your answer.) dMg = 1.738 g/mL, dAl = 2.700 g/mL, dZn = 7.140 g/mL

  13. How long must a current of 0.600 A be passed through a cell containing molten BeCl2 to produce 50.00 g of Be metal?

  14. Calculate the EMF for the voltaic cells below:

    1. Al(s)|Al3+(1 M, aq)|KCl(sat'd)|Co2+(1 M, aq)|Co(s)
    2. Cd(s)|Cd2+(0.500 M,aq)|KCl (sat'd)|Sn2+(1.50 M,aq)|Sn(s)
    3. Cu(s)|Cu2+(1 M, aq)|KCl (sat'd)|Au3+(1 M, aq)|Au(s)

  15. Are the cells below electrolytic or galvanic at standard conditions?

    1. Zn|Zn2+|sat'd KCl|Mg2+|Mg
    2. Cd|Cd2+|sat'd KCl|Ag+|Ag

  16. How much silver will be plated out on an electrode if 5.00 amperes are passed through a silver nitrate solution for 37.0 minutes? Assume that there is plenty of silver nitrate available in the solution.

  17. Balance the redox equations below in acid:

    1. MnO4- + Al -----> Mn2+ + Al3+
    2. BrO3- -----> Br- + BrO4-
    3. Cr2O72- + Sn2+ -----> Cr3+ + Sn4+
    4. IO4- + Mn -----> I2 + Mn2+
    5. Cr6+ + Br2 -----> Cr3+ + BrO3-

  18. Balance the redox equations below in base:

    1. Pb + Ag2O -----> Ag + PbO2
    2. BrO- -----> Br- + BrO3-
    3. Zn + MnO4- -----> MnO2 + Zn2+
    4. Li + Zn(OH)2 -----> LiOH + Zn
    5. Au3+ + MnO2 -----> Au + MnO4-


  19. What is the molar concentration of a solution of Na2Cr2O7, if 25.00 ml of this solution is titrated with 36.89 mL of 2.688 M SnCl2 solution in acid? The approriate unbalanced half-reactions are shown below.

    Cr2O72- ---------> Cr3+ in acid

    Sn2+ ---------> Sn4+


  20. Define:

    1. equilibrium
    2. equilibrium expression
    3. equilibrium constant KC
    4. equilibrium constant, KP
    5. LeChatelier's principle
    .