Chemistry 111

Exam 5

Name___________________

1. Fill in the table. Include hybridization and geometry about each central atom.

Molecule	Lewis Structure	Geometry	hybridization	Polar ?
CH3COCH3 (link the C’s)
CH2F2
ClO3^–
Br2SO
IBr3
NO2^–

2. Scientists have been unable to make the following molecules. Suggest a reason why?

(A) ClO₂

(B) NH₄

(C) NF₅

3. Order the following from the shortest to the longest carbon to oxygen bond.

CO CO₃^2– CH₃OH CO₂.

________ ________ ________ ________

shortest longest

4. Identify a possible element X in each of the following.

F

(A) F − X − F

F

O

(B) [ O = X − O ] ^2¾

5. Rank from the most polar to the least polar bond?

P – N, P – O, P – P, P – S

________ > ________ > ________ > ________

most polar least polar

6. Draw three possible resonance structures for NNO or (NON ) Using formal charges, predict which structure will be the best.

7. Count electrons for C₂H₄O₂N₄, fill in the bonds and lone pairs. How many pi (p) and sigma (s) bonds are in the molecule?

H₂N

C ¾ N O

O N ¾ C

NH₂

8. Estimate ΔH_rxn for: CH₃OH ® 2H₂ + CO:

Given the following bond energies:

H – H 432 kJ/mole

C=O 1072 kJ/mole

O – H 436 kJ/mole

C – H 413 kJ/mole

C – O 358 kJ/mole