Born-Haber Cycles.

Question 1

What is a Born-Haber cycle used for?

Answer 1

When u can’t measure a lattice enthalpy directly allowing u to find out what the enthalpy change would be if u took a less direct route. To get from the element in their standard states to ionic lattice.

Question 2

What is the direct route?

Answer 2

Enthalpy of formation.

Question 3

What’s the process of the indirect route?

Answer 3

1. Enthalpy of formation.⬆️
2. Enthlpies of atomisation and ionisation energy⬆️ places above this.
   ➡️
3. The electron affinity.⬇️
4. The lattice enthalpy.⬇️

Question 4

What is Hess’s law?

Answer 4

The total enthalpy change of a reaction is always the same, no matter which route is taken.

Question 5

How would u work out lattice enthalpy change of formation? 🔺️H6

Answer 5

-🔺️H5-🔺️H4-🔺️H3-🔺️H2+🔺️H1.

Question 6

What signiificane does the direct of the arrows have when working out an enthalpy change.

Answer 6

When going against an arrow you introduce a minute sign, following an arrow is a plus sign.

Question 7

What extra steps is involed when group 2 elements are involed? And why are these steps required?

Answer 7

Group 2 elements form 2+ ions so u need to include second ionisation energy.

The atomisation enthalpy needs to be multiplied by however moles of the element there is in 1 mole of the ionic lattice.