CI 4'6 BornHaber Cycle

1
CI 4.6 Born-Haber Cycle
(C) JHUDSON 2005
2
What do we mean by lattice enthalpy?
For an ionic compound the lattice enthalpy is the
enthalpy change when one mole of solid in its
standard state is formed from its ions in the
gaseous state.
For an ionic compound the lattice enthalpy is the
enthalpy change when one mole of solid in its
standard state is formed from its ions in the
gaseous state.
The lattice enthalpy cannot be measured directly
and so we make use of other known enthalpies and
link them together with an enthalpy cycle.
This enthalpy cycle is the Born-Haber cycle.
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kJmol-1
Born-Haber Cycle for Sodium Chloride
800
700
1 Sublimation of Sodium
600
500
400
300
200
Na(g) 1/2 Cl2(g)
100
Na(s) 1/2 Cl2(g)
0
4
Born-Haber Cycle for Sodium Chloride
kJmol-1
800
700
600
2 Bond Dissociation of Chlorine
500
400
300
Na(g) Cl(g)
200
Na(g) 1/2 Cl2(g)
100
Na(s) 1/2 Cl2(g)
0
5
Born-Haber Cycle for Sodium Chloride
kJmol-1
800
Na(g) Cl(g)
700
e-
600
e-
3 First Ionisation of Sodium
500
e-
400
e-
e-
300
Na(g) Cl(g)
200
Na(g) 1/2 Cl2(g)
100
Na(s) 1/2 Cl2(g)
0
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Born-Haber Cycle for Sodium Chloride
kJmol-1
800
800
800
Na(g) Cl(g)
700
700
700
4 Electron Affinity of Chlorine
600
600
600
500
500
500
400
400
400
Na(g) Cl-(g)
300
300
300
Na(g) Cl(g)
Na(g) Cl(g)
Na(g) Cl(g)
200
200
200
Na(g) 1/2 Cl2(g)
Na(g) 1/2 Cl2(g)
Na(g) 1/2 Cl2(g)
e-
100
100
100
Na(s) 1/2 Cl2(g)
Na(s) 1/2 Cl2(g)
Na(s) 1/2 Cl2(g)
0
0
0
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Born-Haber Cycle for Sodium Chloride
kJmol-1
800
800
800
Na(g) Cl(g)
700
700
700
600
600
600
500
500
500
400
400
400
Na(g) Cl-(g)
300
300
300
Na(g) Cl(g)
Na(g) Cl(g)
Na(g) Cl(g)
200
200
200
Na(g) 1/2 Cl2(g)
Na(g) 1/2 Cl2(g)
Na(g) 1/2 Cl2(g)
100
100
100
Na(s) 1/2 Cl2(g)
Na(s) 1/2 Cl2(g)
Na(s) 1/2 Cl2(g)
0
0
0
5 Formation of Sodium Chloride
NaCl(s)
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Born-Haber Cycle for Sodium Chloride
kJmol-1
800
800
800
Na(g) Cl(g)
700
700
700
600
600
600
500
500
500
400
400
400
Na(g) Cl-(g)
300
300
300
Na(g) Cl(g)
Na(g) Cl(g)
Na(g) Cl(g)
Lattice Enthalpy for Sodium Chloride
200
200
200
Na(g) 1/2 Cl2(g)
Na(g) 1/2 Cl2(g)
Na(g) 1/2 Cl2(g)
100
100
100
Na(s) 1/2 Cl2(g)
Na(s) 1/2 Cl2(g)
Na(s) 1/2 Cl2(g)
0
0
0
NaCl(s)