Question

Calculate the lattice energy of KCl from the given data: Interionic separation = 314pm, born exponent for Ar configuration = 9, Madelung constant(M) = 1.746

a) 2311 kJ/mol
b) 3121 kJ/mol
c) 1902 kJ/mol
d) 1472 kJ/mol

Answer 1

The lattice energy of KCl can be calculated using the formula Lattice energy = M * k * (Q1 * Q2) / d^n, where M is the Madelung constant, k is a proportionality constant, Q1 and Q2 are the ionic charges, d is the interionic separation, and n is the Born exponent. Substituting the given data into the equation, the lattice energy of KCl is approximately 1472 kJ/mol (option d).

Step-by-step explanation:

The lattice energy of an ionic compound can be calculated using the equation:

Lattice energy = k * (Q1 * Q2) / d

where k is a proportionality constant, Q1 and Q2 are the ionic charges, and d is the interionic separation. The Madelung constant (M) is also required for this calculation. The equation is modified as follows:

Lattice energy = M * k * (Q1 * Q2) / dn

Given the data:

Interionic separation = 314 pm

Born exponent (n) for Ar configuration = 9

Madelung constant (M) = 1.746

We can substitute these values into the equation to calculate the lattice energy of KCl:

Lattice energy = 1.746 * k * (1 * 1) / 3149

Calculating this expression answers approximately 1472 kJ/mol (option d).