Question #120796

The values of lattice energies (kJ/mol) for NaCl and AgCl are given below as calculated from

Born-Haber Cycle and Born-Lande equation, respectively.

U(B-H) U(B-L)

NaCl 787 751

AgCl 915 734

a) Why is the value for the lattice energy in each case, greater from Born-Haber cycle than that

from the Born-Lande equation?

b) What is the percentage difference between the two values for NaCl and AgCl? Rationalize

this on the basis of the difference in electronegativities of Na:Cl and Ag:Cl.

Born-Haber Cycle and Born-Lande equation, respectively.

U(B-H) U(B-L)

NaCl 787 751

AgCl 915 734

a) Why is the value for the lattice energy in each case, greater from Born-Haber cycle than that

from the Born-Lande equation?

b) What is the percentage difference between the two values for NaCl and AgCl? Rationalize

this on the basis of the difference in electronegativities of Na:Cl and Ag:Cl.

Expert's answer

**Answer:**

a) Born-Lande equation does not take into account the covalent component of the cation–anion bonds, as a result of which the obtained energies of the crystal lattices have underestimated values.

b) The percentage difference between the two values for NaCl and AgCl is:

for NaCl: "\\frac{787-751}{787}=0.046=4.6%" %

for AgCl: "\\frac{915-734}{915}=0.198=19,8" %

So, we can see that In the case of NaCl, the error of the approximate Born-Lange equation is small. This shows that NaCl is almost close to the ideal ionic compound. For AgCl, the error is large, since **Ag atoms are much more electronegative then Na atoms.** Accordingly, chemical bonds in the AgCl crystal lattice have a significant covalent component.

Learn more about our help with Assignments: Inorganic Chemistry

## Comments

## Leave a comment