The net potential energy EN between two adjacent ions, is sometimes represented by the expression EN = -(C/r) + D exp(-r/rho)

in which r is the interionic separation and C, D, and rho are constants whose values depend on the specific material.

Required:
a. Derive an expression for the bonding energy E0 in terms of the equilibrium interionic separation r0 and the constants D and rho using the following procedure:

1. Differentiate EN with the respect to r and set the resulting expression equal to zero.
2. Solve for C in terms of D, rho, and ro.
3. Determine the expression for Eo by substitution for C in the equation EN = -(C/r) + D exp(-r/rho)

b. Derive another expression for Eo in terms of ro, C, and rho using a procedure analogous to the one outlined in part (a).

The following are the solution to this question:

Explanation:

Total energy capacity EN from adjacent ions is:

where the value of "C, D, and "r is constants.

In point a:

Differentiating EN:

In point b:

The above equation is equal to zero to get the value of C:

The value is replaced by the C value in (1):

The value is replaced by the D value in (1):

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. completely dissociates to and ions. a is incorrect because does not fully ionize to and ions and some remain as the compound . c and d are incorrect because, and do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise,   if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both and have a complete octet so can not accept any electrons which disqualifies them as acids.