Chemistry 401

Intermediate Inorganic Chemistry

University of Rhode Island

Exam 2

November 14, 2011
open book

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.

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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.

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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)

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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.

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