Question

2-1. Consider ionically bonded NaCl. The constants describing the bond energy are:

A = 1.436 (Eq. 2.9)

B = 7.32 x 10^-6 (Eq. 2.11)

n = 8

Where the units of distance are assumed to be nm and the energies are in eV.

(a) Determine the equations for the force of attraction (FA) and force of repulsion (FR).

(b) Determine the interatomic separation that results in zero net force (FN).

(c) Calculate that the net energy at the distance calculated in (b).

(d) Show that an interionic separation of 0.282 nm the results in a maximum net force. (Hint: use a basic principle of calculus to find the equation for the maximum net force.)

Answer 1

We will be using the basic equation of interionic separation i.e.

U(r) = -A/r(attractive) + B/rn(repulsive)