Born Haber Process for BaI2?

Question

List the individual steps used in constructing a Born - Haber cycle for the formation of BaI2 from the elements. Which of the steps would you expect to be exothermic?

Write chemical equation for first step of a Born - Haber cycle.
Express your answer as a chemical equation. Identify all of the phases in your answer.

My Answer:

Ba(s)+I2(s)→BaI2(s)

Apparently it's incorrect. I don't get why.

Answer 1

A Born - Haber cycle is a diagram used to determine the change in enthalpy of a reaction. It describes the relative energy levels required to transform a reacting species in its natural state to an ionized gaseous state (i.e. your neutral solid becomes a plasma). The species then react in the plasma state to form the products.

 

For your reaction, I expect it to look something like this:

 

Ba (s) --> Ba (l) --> Ba (g) --> Ba+ (g) + 1e- --> Ba2+ (g) + 1e-

 

+

 

I2 (s) --> I2 (l) --> I2 (g) 2e- --> 2I- (g)

 

--> BaI2 (s)

 

The cycle is typically a diagram: https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Born-haber_cycle_LiF.svg/2000px-Born-haber_cycle_LiF.svg.png

 

I hope this helps!