1. The sphalerite and wurtzite forms of ZnS are structurally similar: in sphalerite the Zn2+ ions occupy Td holes in a ccp lattice and in wurtzite the Zn2+ ions occupy Td holes in a hcp lattice. Use the Born-Landé equation to predict the thermodynamically more stable form of ZnS. Possibly helpful information: n = 9 for ZnS; r+ = 75 pm; r– = 170 pm; Noe2/4πεo = 1.389×10–4 J m/mole.
2. For H3PO3, pKa1 ~ 2 and for H3AsO3, pKa1 ~ 9. Use Pauling's rules to suggest a structure for each acid. Find the point group for each acid based on your structure.
3. Predict the products and balance the equation for the following reactions:
a. SO3(g) + H2O(l)
b. Na2O(s) + H2O(l)
c. [Fe(SCN)6]3–(aq) + NH3(g)
4. Using the Latimer Diagram for Re in a basic solution, find the standard reduction potential for the conversion of ReO2 to Re. Write the balanced half-reaction.