BORN-HABER CYCLE NOTES

BORN-HABER
CYCLE

Prepared by:
CHEMTitans
Chemistry Unit, KMPh

Table of Content:

Types of Born-Haber Cycle ……....…....3 Video of Example 1……..……….….10
Thermochemical Equation ……………...4 Example 1………………………….11-13
Types of Enthalpy ………………...……...5 Video of Example 2……..…….……14
Example 2………………………….15-16
Steps Construct Energy Cycle Diagram..6 Video of Example 3………………....17
Example 3…………………..………18-20
Steps Construct Energy Level Diagram..7
Tips …………………………..……….…...8
Formula ……………………………..….…9

Two types of
Born-Haber Cycle

1 Energy Cycle Diagram
2 Energy Level Diagram

3

TIPS

1 Thermochemical equation is a chemical equation that includes
the value of ΔH and sign (+ @ -).

Identify all the thermochemical equation for:

PF Enthalpy of Formation ∆Hf 4
H Enthalpy of Atomisation/ Sublimation ∆Ha
A Ionisation energy IE
SA Electron affinity
E Lattice energy EA
∆Hlattice
I
I
N
SE
I
S
TL

F
A
I
E
L

5

TIPS

2 Construct Born-Haber energy cycle diagram:

Step 1: F Enthalpy of Formation
Step 2: A Enthalpy of Atomisation (metal & non-metal)
Step 3: I Ionisation energy (metal: IE1 & IE2)
Step 4: E Electron affinity (non-metal: EA1 & EA2)
Step 5: L Lattice energy

6

3 Construct Born-Haber energy level diagram:
Step 1: F Enthalpy of Formation

Step 2: A Enthalpy of Atomisation (metal & non-metal)

Step 3: I Ionisation energy (metal: IE1 & IE2)

Step 4: E Electron affinity (non-metal: EA1 & EA2)

Step 5: L Lattice energy

Types of chemical reaction Movement of Heat “Enthalpy diagram”
∆H = +ve
∆H = +ve From surrounding to

Endothermic energy absorbed system

∆H = -ve From system to ∆H = -ve
Exothermic energy released surrounding

7

TIPS

4 State all the phase change that exist and the value of enthalpy with sign
and correct unit.

5 When a thermochemical equation is reversed, the sign of ∆H is changed.

When a thermochemical equation is multiplied, ∆H is also multiplied.
6

Let 1 mole represent or

Example:

1/2Cl2 (g) Cl (g) ∆Ha = +122 kJmol-1 8
Cl2 (g) 2Cl (g) ∆Ha x 2 = +122 x 2 kJmol-1

TIPS

7 Formula:
∆Hf XY = ∆Ha X + ∆Ha Y + IE X + EA Y + ∆Hlattice XY

F A IE L

9

https://youtu.be/ZRw5FQS7rEA 2) Energy level diagram

1) Energy cycle diagram

EA Y

IE X

IE X EA Y

∆Hf XY = ∆Ha X + ∆Ha Y + IE1 X + EA Y + ∆Hlattice XY 10

Example 1:

The following data are given:

Enthalpy kJmol-1
Enthalpy of formation of sodium bromide -360
Enthalpy of atomisation/ sublimation of sodium 107
Enthalpy of atomization of bromine 97
Ionisation energy of sodium 496
Electron affinity of bromine -324

a) Write the thermochemical equations for all the enthalpies involved above. 11
b) Construct Born-Haber cycle for NaBr using energy cycle diagram and

energy level diagram.
c) Calculate the Lattice energy for NaBr

Solution: ∆Hf NaBr = -360 kJmol-1
∆Ha Na = +107 kJmol-1
a) Na(s)+ 1/2Br2(g) → NaBr(s) ∆Ha Br = +97 kJmol-1
Na(s) → Na(g) IE of Na = +496 kJmol-1
1/2Br2(g) → Br(g) + e- EA of Br = -324 kJmol-1
Na(g) → Na+(g) + e
Br(g) + e → Br-(g) 12

b)

c)

13

https://youtu.be/T_wUs42l19c

1) Energy Cycle Diagram 2) Energy Level Diagram

∆Hf XY2 EA Y x 2
∆Ha Y x 2
∆Ha X IE2 X

IE1 X EA Y x 2 ∆Hlatice XY2 IE1 X
IE2 X
∆Ha Y x 2 ∆Hlatice XY2
∆Ha X
14
∆Hf XY2

∆Hf XY2 = ∆Ha X + (∆Ha Y x 2) + IE1 X + IE2 X + (EA Y x 2) + ∆Hlattice XY2

Example 2:

The thermochemical equation and enthalpy of the reaction are given below:

Ca(s)+ Cl2(g) → CaCl2(s) ∆Hf CaCl2 = -796 kJmol-1
Ca(s) → Ca(g) ∆Ha Ca = +178 kJmol-1
Ca(g) → Ca+(g) + e- IE1 Ca = +590 kJmol-1
Ca+(g) → Ca2+ (g) + e- IE2 Ca = +1150 kJmol-1
1/2 Cl2(g) → Cl(g) ∆Ha Cl = +122 kJmol-1
Cl(g) + e - → Cl-(g) EA1 Cl = -349 kJmol-1

a) Construct Born-Haber cycle for CaCl2 using energy cycle diagram and
energy level diagram.

b) Calculate the Lattice energy for CaCl2.

15

16

https://youtu.be/nAIr2H2kvDI

1) Energy Cycle Diagram 2) Energy Level Diagram

∆Hf XY EA1 Y EA2 Y
∆Ha Y
∆Ha X IE2 X
IE1 X
IE2 X EA1 Y -∆Hlatice XY IE1 X -∆Hlatice XY
EA2 Y
∆Ha Y
∆Ha X
∆Hf XY

∆Hf XY2 = ∆Ha X + ∆Ha Y + IE1 X + IE2 X + EA1 Y+ EA2 Y - (-∆Hlattice XY) 17

Example 3:

Magnesium oxide solid is formed from the reaction between magnesium and
oxygen gas.

Enthalpy kJmol-1
Enthalpy of atomisation of magnesium +150
First ionisation energy of magnesium +736
Second ionisation energy of magnesium +1450
Enthalpy of atomisation of oxygen +248
First electron affinity of oxygen –142
Second electron affinity of oxygen +844
Dissociation lattice energy of magnesium oxide +3888

By using the data given, 18
a) Write the thermochemical equations for all the enthalpies involved above.
b) Construct Born-Haber cycle for MgO using energy cycle diagram and energy

level diagram.
c) Determine the enthalpy of formation, f for magnesium oxide.

Solution: ∆Ha Mg = +150 kJmol-1
IE1 Mg = +736 kJmol-1
a) Mg(s) → Mg(g) IE2 Mg = +1450 kJmol-1
Mg(g) → Mg+(g) + e- ∆Ha O = +248 kJmol-1
Mg+(g) → Mg2+(g) + e- EA1 O = -142 kJmol-1
½ O2(g) → O(g) EA2 O = +844 kJmol-1
O(g) + e - → O-(g) -∆Hlattice = +3888 kJmol-1
O-(g) + e - → O2-(g)
MgO(s) → Mg2+(g) + O2-(g)

19

20

The end

Prepared by:
CHEMTitans
Chemistry Unit, KMPh