Which of the following best describes lattice energy?
a. a small amount of energy required to form a lattice ion
b. a small release of energy when an atom becomes a cation
c. a large release of energy that form a crystal structure
d. a large amount of energy created when an anion becomes a lattice ion

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.