Born-Haber Cycle

Question 1

What do you use a Born-Haber cycle to find?

Answer 1

The enthalpy change of a reaction if you take a less direct route

Question 2

What is ΔH1?

Answer 2

Enthalpy of formation

Question 3

What is ΔH2?

Answer 3

Atomisation enthalpy for one element

Question 4

What is ΔH3?

Answer 4

Atomisation enthalpy for the other element

Question 5

What is ΔH4?

Answer 5

First ionisation energy of positive ion

Question 6

What is ΔH5?

Answer 6

Electron affinity for negative ion

Question 7

What is ΔH6?

Answer 7

Lattice enthalpy of formation of ionic compound

Question 8

What is Hess’ law?

Answer 8

The enthalpy change for a reaction will be independent to the route taken

Question 9

What rearranged equation can you use to calculate the lattice enthalpy change of formation?

Answer 9

ΔH6 = -ΔH5-ΔH4-ΔH3-ΔH2+ΔH1

Question 10

What do you do to any arrows which you go along the wrong way?

Answer 10

Add a negative sign

Question 11

What does the purely ionic model of a lattice assume?

Answer 11

All the ions are spherical

Question 12

Why does the experimental lattice enthalpy differ from the theoretical lattice enthalpy?

Answer 12

The positive ions polarise neighbouring negative ions to different extents and the more polarisation there is, the more covalent the bonding will be