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

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In summary, lattice energy is the energy released when an ionic crystal is formed from its constituent ions in the gas phase. It is calculated using Coulomb's law and is a measure of the strength of the ionic bonds in a compound. Lattice energy is significant in determining the stability and properties of ionic compounds, and is influenced by the charges, sizes, and distances of the ions. For LiI, the lattice energy is -765 kJ/mol.
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## 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

## The Attempt at a Solution

Could someone give me a hint?

This should help tremendously:

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

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.

## 1. What is the definition of lattice energy?

Lattice energy is the energy released when an ionic crystal is formed from its constituent ions in the gas phase. It is a measure of the strength of the ionic bonds in a compound.

## 2. How is lattice energy calculated?

Lattice energy can be calculated using Coulomb's law, which takes into account the charges of the ions and the distance between them. The equation is: Lattice energy = (k * Q1 * Q2)/d, where k is a constant, Q1 and Q2 are the charges of the ions, and d is the distance between them.

## 3. What is the significance of lattice energy?

Lattice energy is significant because it helps determine the stability and properties of ionic compounds. Compounds with higher lattice energies tend to have stronger bonds and are more stable, making them less likely to break apart into their constituent ions.

## 4. What factors affect the lattice energy of a compound?

The lattice energy of a compound is affected by the charges of the ions, their sizes, and the distance between them. Generally, compounds with higher charges, smaller ions, and shorter distances between ions will have higher lattice energies.

## 5. What is the lattice energy of LiI given the information below?

The lattice energy of LiI is -765 kJ/mol.

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