1.Use bond energies (kJ/mol) to calculate the DH for the following reaction:                                           CO2 + 2NH3 à urea (H2NCONH2) + H2O. The following are the bond dissociation energies for some bonds.

Bond   Dissociation Energy              Bond   Dissociation Energy

N-H    388                                         C=O   743

O-H    463                                         C-N    293

C-O    358                                         C=N    615

2. Draw a valid Lewis structure for the following compounds. You must include all formal charges on all atoms. You must also include lone pairs on the central atom (not for the other atoms). The H is bonded to O in the acids below.

NO2-, CO, H2SO4, H3PO4

3.Draw at least 2 resonance structures for each of the following. Assume the octet rule is obeyed by all elements. You must include all formal charges on all atoms. You must also include lone pairs on the central atom (not for the other atoms).

HCO2-, NO3-, N2O, O3

4a. Describe the shape (linear, bent, trigonal planar, trigonal pyramid, tetrahedral, trigonal bipyramid, see-saw, T shaped, octahedron, square, square pyramid) for each of the following molecules:        SO3            BrF3   

4b. State whether each of the following molecules are polar or non- polar: XeF4    HCN       

5     Use the molecular orbital diagram below to predict the bond order and number of unpaired electrons in each of the following.

compound/ion            bond order                  # of unpaired electrons

NO

O22-