Chemistry 401

Intermediate Inorganic Chemistry

University of Rhode Island

Exam 2

November 6, 2009
open book, open notes

1. MgO is found in the rock salt (NaCl) structure with a lattice constant of 421.2 pm. Is this consistent with the ionic radii given in the textbook? Explain.


2. The band gap in MgO is 7.8 eV. Is MgO likely to be an effective semiconductor? Why or why not? What could you dope MgO with to form a p-type semiconductor? An n-type semiconductor? Explain your reasoning in each case.


3. In terms of Brønsted-Lowry theory, do you expect MgO to be an acid, a base, or a neutral compound? Explain.


4. Predict if the following reactions occur. If reaction does occur, balance the reaction.

a. MgO(s) + HF(aq)

b. MgO(s) + H2S(aq)


5. MgO can be formed by dehydration of Mg(OH)2. Using data from Latimer Diagrams and a Born-Haber (or thermochemical) cycle, find ΔG° for the dehydration reaction of Mg(OH)2. ΔGf° for MgO is –569.4 kJ/mol (this is for the formation of MgO from the elements). ΔG° = –nFE°.