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General Chemistry Principles, Patterns, and Applications, 2011

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6. How would the lattice energy of an ionic compound consisting of a monovalent cation <strong>and</strong> a divalent anion<br />

compare with the lattice energy of an ionic compound containing a monovalent cation <strong>and</strong> a monovalent<br />

anion, if the internuclear distance was the same in both compounds? Explain your answer.<br />

7. Which would have the larger lattice energy—CrCl 2 or CrCl 3 —assuming similar arrangements of ions in the<br />

lattice? Explain your answer.<br />

8. Which cation in each pair would be expected to form a chloride salt with the larger lattice energy, assuming<br />

similar arrangements of ions in the lattice? Explain your reasoning.<br />

a. Na + , Mg 2+<br />

b. Li + , Cs +<br />

c. Cu + , Cu 2+<br />

9. Which cation in each pair would be expected to form an oxide with the higher melting point, assuming similar<br />

arrangements of ions in the lattice? Explain your reasoning.<br />

a. Mg 2+ , Sr 2+<br />

b. Cs + , Ba 2+<br />

c. Fe 2+ , Fe 3+<br />

10. How can a thermochemical cycle be used to determine lattice energies? Which steps in such a cycle require<br />

an input of energy?<br />

11. Although NaOH <strong>and</strong> CH 3 OH have similar formulas <strong>and</strong> molecular masses, the compounds have radically<br />

different properties. One has a high melting point, <strong>and</strong> the other is a liquid at room temperature. Which<br />

compound is which <strong>and</strong> why?<br />

N U M E R I C A L PR O BL E M S<br />

1. Arrange SrO, PbS, <strong>and</strong> PrI 3 in order of decreasing lattice energy.<br />

2. Compare BaO <strong>and</strong> MgO with respect to each of the following properties.<br />

a. enthalpy of sublimation<br />

b. ionization energy of the metal<br />

c. lattice energy<br />

d. enthalpy of formation<br />

3. Use a thermochemical cycle <strong>and</strong> data from Figure 7.13 "Electron Affinities (in kJ/mol) of the ", Table 7.5<br />

"Successive Ionization Energies (in kJ/mol) for the Elements in the Third Row of the Periodic Table", Table 8.2<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

695

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