Department of Chemistry

CARNEGIE MELLON UNIVERSITY

Introduction to Modern Chemistry (09-105)

EXAM II Name

October 14, 1998 Circle Section A B C D E F G H J K L

Closed book. Show all work.

No equations stored in calculators. No notes.

Don't throw away points using significant figures and units incorrectly!

H                                 2He
Li Be                     B C N O F 10Ne
Na Mg                     Al Si P S Cl 18Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br 36Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I 54Xe
Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At 86Rn
Fr Ra Ac* Rf Ha Sg Bh Hs Mt 110 111 112            
Qe = 1.6022 € 10-19 C (unit of charge)

1 D (debye) = 3.336 € 10-30 C . m

1 pm =10-12 m
1. /25  
2. /25  
3. /25  
4. /25  
/100  

 

1. Arrange the following in order of increasing dipole moment, lowest first. Indicate the sequence by the letters assigned to each structure. (Correct sequence equals full score. One structure out of sequence equals half score. More than one out of sequence gets no score.)

 

 

Orthoperiodic acid, with iodine as the central atom, has the formula OI(OH)5. Will the pK of its hypothetical analog with astatine, OAt(OH)5, be greater, lesser or the same as that for OI(OH)5?

 

 

 

 

What is the oxidation number of iodine in orthoperiodic acid?

 

 

Will periodic acid (HO)IO3 (in which iodine is again central) be a stronger or weaker acid than orthoperiodic acid?

 

 

 

 

The most stable compound between oxygen and fluorine has the formula OF2. What is the oxidation number of oxygen in this compound?

 

 

2. The hydrogen-potassium bondlength in HK is 152 pm. The dipole moment is measured to be 6.13 D (debyes). Calculate the fractional ionic character of the HK bond.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What is the oxidation number of potassium in this compound?

 

 

If the fractional ionic character of barium sulfide, BaS, were found to be exactly 0.50, which of the following would best be cited as the complete, preferred Lewis structure?

This past Monday, the Nobel Prize in Medicine was announced and concerns the discovery of the many roles played by nitric oxide (NO) in physiological systems. What is the complete, preferred Lewis structure for NO?

 

 

3. As mentioned in problem 1, orthoperiodic acid, with iodine as the central atom, has the formula OI(OH)5. When it is completely ionized, the IO65- ion is produced. Draw the complete, preferred Lewis structure for this latter ion, the orthoperiodate ion.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What is the iodine-oxygen bond order for each of the six iodine-oxygen bonds?

 

 

 

 

 

 

 

 

When the acid is incompletely ionized, one of the intermediate species is the ion [O3I(OH)3]2- still with iodine as the central atom. What are the iodine-oxygen bond order for each of the six iodine-oxygen bonds in this ion?

 

4. Below is the structure of nicotine. For the three angles indicated by the italic numbers 1, 2, and 3, what are the best values you should be able to give?

 

angle 1 is _______________________

angle 2 is _______________________

angle 3 is _______________________

 

What are the molecular geometry names and the best estimates that you should be able to give for the FXF bond angles in each of the molecules below (where X just represents the central atom)?

 

molecule

molecular geometry

FXF angle
   

CF4

    

NF3

    

XeF2