Chapter 8, Problem 1PE

Choose the ionic compound that would have the larger lattice energy: $\left(\text{a}\right){\text{ LiBr or CaBr}}_{\text{2}}\text{, }\left(\text{b}\right)\text{ LiF or KF, }\left(\text{c}\right)\text{ CaO or BaS}\text{.}$ (Hint: What two factors affect lattice energy?)

Interpretation Introduction

Interpretation:

The ionic compound that has the larger lattice energy from the given compounds is to be identified.

Concept Introduction:

An ionic compound is a compound in which positive and negative ions are held together by electrostatic forces.

Lattice energy is the energy that is liberated when ions are linked together in order to form a compound.

Lattice energy increases with the increase in the charge of the ions and the decrease in the size of the ions.

Answer to Problem 1PE

Solution:

a) ${\text{CaBr}}_{\text{2}}$

b) $\text{LiF}$

c) $\text{CaO}$

Explanation of Solution

a) $\text{LiBr}$ or ${\text{CaBr}}_{\text{2}}$

When the charges on the ions become greater, the potential energy is considered to be lower that leads to a larger lattice energy. The ionic compound ${\text{CaBr}}_{\text{2}}$ carries a greater charge than the ionic compound $\text{LiBr}$, which means ${\text{CaBr}}_{\text{2}}$ contains larger lattice energy.

b) $\text{LiF}$ or $\text{KF}$

When the size of the ions become smaller, the potential energy is considered to be higher that leads to a larger lattice energy. The ionic compound $\text{LiF}$ has a smaller size than the ionic compound $\text{KF}$, which means $\text{LiF}$ contains larger lattice energy.

c) $\text{CaO}$ or $\text{BaS}$

When the charges on the ions become greater, the potential energy is considered to be higher that leads to a larger lattice energy. The ionic compound $\text{CaO}$ carries a greater charge than the ionic compound $\text{BaS}$ because the Oxygen atom has more charge than the Sulphur atom, which means $\text{CaO}$ contains larger lattice energy.