Name: ____________________

CHEM&143 – FINAL EXAM – Summer 2008 – 194 Points

Valuable constants and equations are on the last page

 

1.  Which of these nuclides is most likely to be radioactive? (5 points)

a.        

b.     

c.        

d.       

e.      

 

2. 41Ca decays by electron capture. The product of this reaction undergoes alpha decay. What is the product of this second decay reaction __________? (5 points)

a.       Ti

b.      Ca

c.        Ar

d.      Cl

e.       Sc

 

3. Nuclei above the belt of stability can lower their neutron-to-proton ratio by________. (5 points)

a.       beta emission.

b.      gamma emission.

c.       positron emission.

d.      electron capture.

 

4. Which one of the following is always positive when a spontaneous process occurs? (5 points)

a.                   ∆Ssystem 

b.                  ∆Ssurroundings 

c.                   ∆Suniverse 

d.                  ∆Huniverse 

e.                   ∆Hsurroundings

 

 

 

___________________/20


 

5.Of the following, the entropy of gaseous __________ is the largest at 25 °C and 1 atm. (5 points)H2

a.                   C2H6

b.                  C2H2

c.                   CH4

d.                  C2H4 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

6.A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ∆H is __________ and ∆S is __________. (5 points)

a.       +, +

b.      -, -

c.       +, -

d.      -, +

e.       +, 0

 

7. __________ is the oxidizing agent in the reaction below. (5 points)

           

Cr2O72- + 6 S2O32- + 14 H+ → 2 Cr3+ + 3 S4O62- + 7 H2O

 

a.                     Cr2O72-

b.                    S2O32-

c.                     H+

d.                    Cr3+

e.                     S4O62-

8.What is the charge of the central metal ion in Ca3[Fe(CN)6]2 __________? (5 points)

a.       0

b.      1+

c.       2+

d.      3+

e.       6+

 

9.The correct name for Na3[CoF6] is __________. (5 points)

a.       trisodium hexakisfluorocobalt(III)

b.      trisodium hexakisfluorocobalt(II)

c.       trisodium hexakisfluorocobalt(IV)

d.      sodium hexafluorocobaltate(III)

e.       sodium hexafluorocobaltate(IV)

 

 

 

 

 

 

 

 

 

_______________/20


 

10. For following compound: dicyanobis(ethylenediamine)chromium(III) bromide. (5 points each – 15 points total)

 

a. Write the formula:

 

 

 

 

b. Provide the correct structure:

 

 

 

 

 

c. Draw the Crystal field splitting diagram for this complex.  Is this a high spin or low spin complex?  Note if the complex should be paramagnetic or diamagnetic.

 

 

 

 

 

 

  1. Name, determine the oxidation state, number of d-electrons, coordination #, for the following complexes: (24 points)

     

Formula

Oxidation State

Coordination

Number

# d electrons

geometry

[Ni(H2O)6]SO4

 

 

 

 

Na2[NiCl4]

 

 

 

 

[Pt(CN)2(NH3)2]I2

 

 

 

 

 

 

 

 

____________/39

  1. Balance the following redox reactions: (10 points each – 20 points each)

a. Al(s) + OH-(aq) → Al(OH)4-(aq) + H2(g) (in basic solution)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

b. MnO2(s) + Cl-(aq) → Mn2+(aq) + Cl2(g)  (in acidic solution)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

______________________/20

13.  For the following reaction at 25°C: (10 points each – 20 points total)

2 Al+3(aq)  +  3 Mg(s) → 2 Al(s)  +  3 Mg+2(aq)

 

a. Determine the cell potential if the magnesium ion concentration is 0.20M and aluminum ion concentration is 0.10M. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

b. Find the equilibrium constant for this reaction.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

_______________/20

 

14.  Write equations for the following processes: (5 points each - 15 points total)

a. the alpha-decay of Polonium-210

 

 

 

 

b. positron emission of Calcium-41

 

 

 

 

c. beta-decay of potassium-42

 

 

 

 

 

 

 

 

15.  A solution of NaF is added dropwise to a solution that is 0.0144 M in Ba2+. (15 points total)

             

a. What must the concentration of F- be to precipitate BaF2? Neglect volume changes. For BaF2, Ksp = 1.7 × 10-6. (10 points)

 

 

 

 

 

 

 

 

 

 

            b. What is the molar solubility of barium fluoride in water?  (5 points)

 

 

 

 

 

 

________________/30

 

16.  Will AgIO3(s) precipitate when 100 mL of 0.010M AgNO3 is mixed with 10 mL of 0.015M NaIO3? Ksp of AgIO3 is 3.1 x 10-8. (10 points)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. Copper (I) chloride, an insoluble salt, can be made soluble by adding ammonia to the solid.  Ksp (CuCl) = 1.0 x 10-6; Kf (Cu(NH3)4+) = 1.1 x 1012.  (20 points)

a.                   Write a balanced equation for the reaction between copper (I) chloride and ammonia. (10 points)

 

 

 

 

 

 

 

 

            b. What is the value of K for this reaction? (10 points)

 

 

 

 

 

 

 

 

 

 

 

 

____________/30

18.   210Pb has a half-life of 22.3 years and decays to produce 206Hg. If you start with 7.50 g of 210Pb, how many grams of 210Pb will you have after 17.5 years? (10 points)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

____________/10

DG°rxn = DH°rxn - TDS°rxn

DGrxn = DG°rxn + R·T·lnQ

DG°rxn = -R·T·lnK

lnK = -DH°/RT + DS°/R

R = 8.314 J/(mol·K)

1 A = 1 C/s

1 V = 1J/C

∆G° = -nFE°cell

F = 96,485 C/mol e-

E°cell = 0.0592 V/n ● log K

Ecell = E°cell- 0.0592 V/n ● log Q

t1/2 = 0.693/k

ln[Nt/N0] = -kt

ln[ratet/rate0] = -kt

1 MeV = 1.602 x 10-13 J

1 amu = 931.5 MeV

U-238 t1/2 = 4.5 x 109 years