Question

Lattice energy of ionic compounds depend upon:
A.packing of ions only
B.charge and size of ions
C.charge on ion only
D.size of ions only

Answer 1

Lattice energy simply can be defined as the energy required to break any lattice. Ionic compounds are formed by the combination of cation and an anion. Keeping these two points in mind one will easily get the correct option of this question.

Complete step-by-step answer: Lattice energy is defined as the heat of formation for ions of opposite charge in the gas phase to combine into an ionic solid. It is directly proportional to the charge on the ions and inversely proportional to the size of the ions.
If the ionic size is large, that means the internuclear distance between the two ions is high. What is the internuclear distance; it is nothing but the bond length. Now the attraction between them is less as the distance is increasing, the attraction between them decreases. So the formation of the compound in the case of larger ions is difficult, whereas in the case of smaller ions the internuclear distance is small.
So what happens here? The force of attraction is very high. This indicates that the size of Cation or anion is inversely proportional to the stability because as the size of the anion increases, the stability of the compound decreases. After all, the ease of formation between them is difficult. So to determine the lattice enthalpy experimentally, we have the Born-Haber cycle which is dependent on the concept called Hess's Law.

So the correct answer to this question is option B.

Note: We should also have a brief idea about lattice enthalpy. Lattice enthalpy is the energy released during the formation of one mole of an ionic compound from its gaseous ions. So this energy is always exothermic and the values are negative. Thus, more the lattice energy, more is the stability of the compound.