The lattice energy for ionic crystals increases as the charge on the ions and the size of the ions . a. increases, increases
b. increases, decreases
c. decreases, increases
d. decreases, decreases
e. none of these ,is generally correct

b. increases, decreases

Explanation:

For an ionic compound ( ionic crystal), the lattice energy accounts for the crystal lattice's cohesion energy.

The lattice energy is the change in molar enthalpy associated with the reaction of the formation of gas ions from a mole of crystal.

This means that the lattice energy is needed to split the bond between particles of a solid ionic crystal and change the atoms into gaseous ions.

The smaller the atom size, the more heat energy required to split the bond, and the larger the atom size, the lesser heat required.

The charge on the atom also affects the behavior of ionic crystals. In essence, the higher the charge on the atom, the more difficult to split the bond, and the lesser the charge on an atom, the easier it is to split the bond.

Thus, we can conclude that the lattice energy for ionic crystals increases as the ions' charge increases, and the size of the ions decreases.

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"

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