What is the lattice energy of LiI? Given the information below.

[stacker]

Homework Statement

What is the lattice energy of LiI? Given the information below.

Heat of formation for LiI = -270 kJ/mol

Heat of sublimation for Li = 159.40 kJ/mol

Ionization energy for Li = 520 kJ/mol

Bond dissociation energy for I2 = 149 kJ/mol

Electron affinity for I = - 295 kJ/mol

Heat of sublimation for I2 = 48.30 kJ/mol

Homework Equations

The Attempt at a Solution

Could someone give me a hint?

 

[nickdk]

This should help tremendously:

http://answers.yahoo.com/question/index?qid=20080121195206AA88t5P

 

[kerimek]

I would first clarify the question and make sure I have all the necessary information. The lattice energy of a compound is the energy required to completely separate one mole of a solid ionic compound into its constituent ions in the gas phase. In order to calculate the lattice energy of LiI, we need to use the Born-Haber cycle, which takes into account the various energies involved in the formation of the compound.

First, we can use the heat of formation to determine the enthalpy change for the formation of LiI from its constituent elements, Li and I. This would be -270 kJ/mol, as given in the information.

Next, we need to consider the energy required to convert solid Li and I into their gaseous state, which is the heat of sublimation. This would be 159.40 kJ/mol for Li and 48.30 kJ/mol for I2, as given in the information.

We also need to consider the energy required to ionize Li and I, which is the ionization energy for Li and the electron affinity for I, respectively. This would be 520 kJ/mol for Li and -295 kJ/mol for I, as given in the information.

Finally, we need to consider the energy released when the bond between the two atoms in the compound is broken, which is the bond dissociation energy for I2. This would be 149 kJ/mol, as given in the information.

Using all of this information, we can construct the Born-Haber cycle and calculate the lattice energy of LiI. The exact calculation is beyond the scope of this response, but the final answer will be a negative value, indicating that the process of forming LiI from its constituent elements is exothermic and the compound is stable.