Hour Exam #3.  Chemistry 104            Name _________________________
A. Rheingold, Dec. 10, 1996                  Section ________________________

I.  (2 pts @) Complete and balance the following reactions (if no reaction occurs, indicate
with "NR"):

     (a)  P4O10(s)  +  H2O    

     (b)  CaO(s)  +  H2O    
                    
     (c)  P4O10(s) +  CaO(s)     (@ 400øC)

     (d)  H3PO4(aq)  +  Ca(OH)2(aq)   

     (e)  SO2(OH)2(aq)  +  Ca(OH)2(aq)   

     (f)  H2SO4(aq)  +   Ca(OH)2(aq)    

     (g)  Ni(s)  +  CO(g)    

     (h)  CaC2(s)  +  H2O    

     (i)  MnO2(s)  +  HCl(aq)    

     (j)  Al(s)   +   Fe2O3(s)      


II.  (2 pts @) Write complete and balanced equations to represent the following:

     (a)  Burning white phosphorus in air

     (b)  Burning diamonds in air

     (c)  The reaction between ammonia- and chlorine-releasing cleaning products

     (d)  The Mond process

     (e)  The chromate/dichromate equilibrium

     (f)  The hydrolysis of dimethyldichlorosilane, (CH3)2SiCl2

     (g)  The thermal decomposition of sodium azide (hint: air bags)

     (h)  Any reaction producing chlorine as a product

     (i)  The hydrolysis of CrO3

III.  (3 pts @)  Define briefly and give examples where appropriate.

     (a)  allotrope



     (b)  inert-pair effect



     (c)  chelating ligand



     (d)  crystal (ligand) field stabilization energy



     (e)  cis-platin



IV.  (6 pts)  Your text refers to the porphyrin ligand as "one of nature's favorite."  In a few
     sentences, explain what features of the ligand could account for its ubiquitous presence in
     bioinorganic compounds.











V.   (6 pts)  {This is a multi-part question.  Be sure you address all parts.}  (1)  Explain
(with
     appropriate drawings) why one of the cis-trans isomers of [CoCl2(en)2] exhibits optical
     isomerism and the other does not.  (2)  Which is which?  







VI.  (6 pts)  Describe some important ways in which mercury differs chemically from zinc
and
     cadmium.  Be specific and use equations to illustrate your answers.









VII. (2 pts @)  Use orbital diagrams to indicate the ground-state valence electron
configurations for
     the following:  (a)  Ti,  (b)  V2+,  (c)  Co3+

     (a)

     (b)

     (c)

VIII.     (9 pts)  {This is a multi-part question.  Be sure you address all parts.}  (1)  Sketch
enough of
          the structures of diamond, graphite and fullerene-60 to show you understand the
chemical
          bonding in each.  (2)  Which is the most electrically conductive and which is the
least and why? 
          (3)  Which is the most highly colored and which is the least and why?  (4)  What is
the
          nominal hybridization of carbon in each?  (5)  Which would you expect to have the
highest
          density and which the least and why?











IX.  (2 pts @)  Write formulas for the following:

     (a)  sodium hexabromocobaltate (III)

     (b)  diamminetetranitrochromate (III)

     (c)  dibromobis(ethylenediamine)palladium {Pd} sulfate

     (d)  manganese(pentacarbonyl) iodide

X.   (6 pts)  For this question we will define a new energy unit called a Blue Hen (BH).  For
a
     certain octahedral transition-metal coordination complex, ML6n+, with a d6 electronic
     configuration, it requires 10 BH to form a pair of electrons in a d orbital.  The crystal
(ligand)
     splitting energy for the separation of the d orbitals in an octahedral field of ligand L is 8
BH. 
     Explain why this complex is likely to be high-spin and paramagnetic.











Extra credit (2 pts @):

(1)  Write the formula for the simplest stable carbonyl complex of rhodium (Rh).



(2)  What structural features do heme and chlorophyll have in common?



(3)  Where is the chlorine in chlorophyll located?



(4)  Why is EDTA frequently found in salad dressing?



(5)  What is EDTA?



(6)  Draw the structure of IX (c)?