IB Chemistry on Born Haber Cycle and Lattice Enthalpy
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Transcript of IB Chemistry on Born Haber Cycle and Lattice Enthalpy
Na (s) Na (g)
Born Haber Cycle/BHC
Li+(g) + CI–
(g) → LiCI (s)
Multi stage Hess’s Cycle Find Lattice enthalpy for IONIC COMPOUND
A → D / A → B → C → D/ ∆H1 = H2 + H3 + H4
∆H1
∆H2 ∆H4
∆H3 Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
LiCI (s) → Li+(g) + CI–
(g)
Li (g) → Li+(g) + e
2nd Ionization enthalpy + ∆H when 1 MOL e removed from
1 MOL unipositive ion in gaseous state
Li+(g) → Li2+
(g) + e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
Na(s) + ½CI2(g) → NaCI(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
Li Li+ + e-
+ e-
Li+ Li2+
+ + 2+
Electron affinity Enthalpy
+ e- -
CI- CI
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
CI (g) + e → CI -(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
Na CI2 NaCI
solid gas
Na(s) → Na(g) ½H2 (g) → H (g) ½O2 (g) → O (g)
½H2 (g) H (g)
1 mol gas
H2 (g) → 2H (g) O2 (g) → 2O (g)
½O2 (g) O (g)
+∆H -∆H
NOT atomization
enthalpy 2 mol gas
gas
LiCI (s)
Li+(g) + CI (g) Li+(g) + CI (g)
Li+(g) + ½CI2 (g)
Li(g) + ½CI2 (g)
LiCI (s)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally)
LiCI (s)
∆H lattice = ????? ( Can’t be determined experimentally)
∆H form = - 409 ( Determined experimentally)
Li(s) + ½CI2 (g)
Born Haber Cycle/BHC
Li+(g) + CI–
(g) → LiCI (s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
LiCI (s) → Li+(g) + CI–
(g)
Li (g) → Li +(g) + e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
Li(s) + ½CI2(g) → LiCI(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
Li Li+ + e-
+
Electron affinity Enthalpy
+ e- -
CI- CI
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
CI (g) + e → CI -(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
Li CI2 LiCI
½CI2 (g) → CI (g)
+∆H -∆H
½CI2 (g) CI (g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
LiCI (s)
Li+ (g) + CI–
(g) Li+ (g) + CI–
(g)
∆Hlatt
∆H form = - 409
Li(s) + ½CI2 (g)
∆Hatom = + 159 Li(s) → Li(g)
Li+(g) + CI-(g)
∆Hie = + 520 Li(g) → Li+ (g)
∆Hatom = + 121 ½CI2(g) → CI(g)
∆He = - 364 CI(g) → CI -(g)
∆Hlatt = -845
NaCI (s)
Na+(g) + CI (g) Na+
(g) + CI (g)
Na+(g) + ½CI2 (g)
Na(g) + ½CI2 (g)
NaCI (s)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally)
NaCI (s)
∆H lattice = ????? ( Can’t be determined experimentally)
∆H form = - 414 ( Determined experimentally)
Na(s) + ½CI2 (g)
Born Haber Cycle/BHC
Na+(g) + CI–
(g) → NaCI (s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
NaCI (s) → Na+(g) + CI–
(g)
Na (g) → Na +(g) + e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
Na(s) + ½CI2(g) → NaCI(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
Na Na+ + e-
+
Electron affinity Enthalpy
+ e- -
CI- CI
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
CI (g) + e → CI -(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
Na CI2 NaCI
½CI2 (g) → CI (g)
+∆H -∆H
½CI2 (g) CI (g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
NaCI (s)
Na+ (g) + CI–
(g) Na+ (g) + CI–
(g)
∆Hlatt
∆H form = - 414
Na(s) + ½CI2 (g)
∆Hatom = + 108 Na(s) → Na(g)
Na+(g) + CI-
(g) ∆Hie = + 500 Na(g) → Na+ (g)
∆Hatom = + 121 ½CI2(g) → CI(g)
∆He = - 364 CI(g) → CI -(g)
∆Hlatt = -790
KCI (s)
K+(g) + CI (g) K+
(g) + CI (g)
K+(g) + ½CI2 (g)
K(g) + ½CI2 (g)
KCI (s)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally)
KCI (s)
∆H lattice = ????? ( Can’t be determined experimentally)
∆H form = - 436 ( Determined experimentally)
K(s) + ½CI2 (g)
Born Haber Cycle/BHC
K+(g) + CI–
(g) → KCI (s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
KCI (s) → K+(g) + CI–
(g)
K (g) → K +(g) + e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
K(s) + ½CI2(g) → KCI(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
K K+ + e-
+
Electron affinity Enthalpy
+ e- -
CI- CI
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
CI (g) + e → CI -(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
K CI2 KCI
½CI2 (g) → CI (g)
+∆H -∆H
½CI2 (g) CI (g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
KCI (s)
K+ (g) + CI–
(g) K+ (g) + CI–
(g)
∆Hlatt
∆H form = - 436
K(s) + ½CI2 (g)
∆Hatom = + 89 K(s) → K(g)
K+(g) + CI-
(g) ∆Hie = + 425 K(g) → K+ (g)
∆Hatom = + 121 ½CI2(g) → CI(g)
∆He = - 364 CI(g) → CI -(g)
∆Hlatt = -720
NaBr (s)
Na+(g) + Br (g) Na+
(g) + Br (g)
Na+(g) + ½Br2 (g)
Na(g) + ½Br2 (g)
NaBr (s)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally)
NaBr (s)
∆H lattice = ????? ( Can’t be determined experimentally)
∆H form = - 361 ( Determined experimentally)
Na(s) + ½Br2 (g)
Born Haber Cycle/BHC
Na+(g) + Br–
(g) → NaBr (s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
NaBr (s) → Na+(g) + Br–
(g)
Na (g) → Na +(g) + e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
Na(s) + ½Br2(g) → NaBr(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
Na Na+ + e-
+
Electron affinity Enthalpy
+ e- -
Br- Br
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
Br (g) + e → Br -(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
Na Br2 NaBr
½Br2 (g) → Br (g)
+∆H -∆H
½Br2 (g) Br (g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
NaBr (s)
Na+ (g) + Br–
(g) Na+ (g) + Br–
(g)
∆Hlatt
∆H form = - 361
Na(s) + ½Br2 (g)
∆Hatom = + 108 Na(s) → Na(g)
Na+(g) + Br-
(g) ∆Hie = + 500 Na(g) → Na+ (g)
∆Hatom = + 112 ½Br2(g) → Br(g)
∆He = - 325 Br(g) → Br -(g)
∆Hlatt = -750
NaF (s)
Na+(g) + F (g) Na+
(g) + F (g)
Na+(g) + ½F2 (g)
Na(g) + ½F2 (g)
NaF (s)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally)
NaF (s)
∆H lattice = ????? ( Can’t be determined experimentally)
∆H form = - 574 ( Determined experimentally)
Na(s) + ½F2 (g)
Born Haber Cycle/BHC
Na+(g) + F–
(g) → NaF (s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
NaF (s) → Na+(g) + F–
(g)
Na (g) → Na +(g) + e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
Na(s) + ½F2(g) → NaF(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
Na Na+ + e-
+
Electron affinity Enthalpy
+ e- -
F- F
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
F (g) + e → F -(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
Na F2 NaF
½F2 (g) → F (g)
+∆H -∆H
½F2 (g) F (g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
NaF (s)
Na+ (g) + F–
(g) Na+ (g) + F–
(g)
∆Hlatt
∆H form = - 574
Na(s) + ½F2 (g)
∆Hatom = + 108 Na(s) → Na(g)
Na+(g) + F -
(g) ∆Hie = + 500 Na(g) → Na+ (g)
∆Hatom = + 79 ½F2(g) → F(g)
∆He = - 328 F(g) → F -(g)
∆Hlatt = -930
NaH (s)
Na+(g) + H (g) Na+
(g) + H (g)
Na+(g) + ½H2 (g)
Na(g) + ½H2 (g)
NaH (s)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally)
NaH (s)
∆H lattice = ????? ( Can’t be determined experimentally)
∆H form = - 57 ( Determined experimentally)
Na(s) + ½H2 (g)
Born Haber Cycle/BHC
Na+(g) + H–
(g) → NaH (s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
NaH (s) → Na+(g) + H–
(g)
Na (g) → Na +(g) + e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
Na(s) + ½H2(g) → NaH(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
Na Na+ + e-
+
Electron affinity Enthalpy
+ e- -
H- H
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
H (g) + e → H -(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
Na H2 NaH
½H2 (g) → H (g)
+∆H -∆H
½H2 (g) H (g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
NaH (s)
Na+ (g) + H–
(g) Na+ (g) + H–
(g)
∆Hlatt
∆H form = - 57
Na(s) + ½H2 (g)
∆Hatom = + 108 Na(s) → Na(g)
Na+(g) + H -
(g) ∆Hie = + 500 Na(g) → Na+ (g)
∆Hatom = + 218 ½H2(g) → H(g)
∆He = - 72 H(g) → H -(g)
∆Hlatt = -811
Mg2+(g) + O (g)
MgO (s) MgO (s)
Mg2+(g) + O (g)
Mg2+(g) + ½O2 (g)
Mg(g) + ½O2 (g)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally)
MgO (s)
∆H lattice = ????? ( Can’t be determined experimentally)
∆H form = - 602 ( Determined experimentally)
Mg(s) + ½O2 (g)
Born Haber Cycle/BHC
Mg2+(g) + O2-
(g) → MgO(s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
MgO(s) → Mg2+(g) + O2-
(g)
Mg(g) → Mg2+(g) + 2e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
Mg(s) + ½O2(g) → MgO(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
Mg Mg2+ + 2e-
2+
Electron affinity Enthalpy
+ 2e- 2-
O2- O
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
O (g) + e → O2-(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
Mg O2 MgO
½O2 (g) → O (g)
+∆H -∆H
½O2 (g) O(g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
MgO (s)
Mg2+ (g) + O2-
(g)
∆Hlatt
∆H form = - 602
Mg(s) + ½O2 (g)
∆Hatom = + 146 Mg(s) → Mg(g)
Mg2+(g) + O2-
(g) ∆H i 1st/2nd = + 2186 Mg(g) → Mg2+
(g)
∆Hatom = + 249 ½O2(g) → O(g)
∆He 1st = - 141
O(g) → O-(g)
∆Hlatt = -3833
Mg2+ (g) + O2-
(g)
∆He 2nd = + 791
O-(g) → O2-
(g)
Ca2+(g) + 2CI (g)
CaCI2 (s) CaCI2 (s)
CaCI2 (s)
Ca2+(g) + 2CI (g)
Ca2+(g) + CI2 (g)
Ca(g) + CI2 (g)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally) ∆H lattice = ?????
( Can’t be determined experimentally)
∆H form = - 795 ( Determined experimentally)
Ca(s) + CI2 (g)
Born Haber Cycle/BHC
Ca2+(g) + 2CI-
(g) → CaCI2(s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
CaCI2(s) → Ca2+(g) + 2CI-
(g)
Ca(g) → Ca2+(g) + 2e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
Ca(s) + CI2(g) → CaCI2(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
Ca Ca2+ + 2e-
2+
Electron affinity Enthalpy
+ e- -
CI- CI
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
CI (g) + e → CI-(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
Ca CI2 CaCI2
½CI2 (g) → CI (g)
+∆H -∆H
½CI2 (g) CI(g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
CaCI2 (s)
Ca2+ (g) + 2CI-
(g)
∆Hlatt
∆H form = - 795
Ca(s) + CI2 (g)
∆Hatom = + 190 Ca(s) → Ca(g)
Ca2+(g) + 2CI-
(g) ∆H i 1st/2nd = + 1730 Ca(g) → Ca2+
(g)
∆Hatom = + 121 x 2 ½CI2(g) → CI(g)
∆He 1st = - 354 x 2
CI(g) → CI -(g)
∆Hlatt = -2249
Ca2+ (g) + 2CI-
(g)
Ba2+(g) + 2CI (g)
BaCI2 (s) BaCI2 (s)
BaCI2 (s)
Ba2+(g) + 2CI (g)
Ba2+(g) + CI2 (g)
Ba(g) + CI2 (g)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally) ∆H lattice = ?????
( Can’t be determined experimentally)
∆H form = - 860 ( Determined experimentally)
Ba(s) + CI2 (g)
Born Haber Cycle/BHC
Ba2+(g) + 2CI-
(g) → BaCI2(s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
BaCI2(s) → Ba2+(g) + 2CI-
(g)
Ba(g) → Ba2+(g) + 2e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
Ba(s) + CI2(g) → BaCI2(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
Ba Ba2+ + 2e-
2+
Electron affinity Enthalpy
+ e- -
CI- CI
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
CI (g) + e → CI-(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
Ba CI2 BaCI2
½CI2 (g) → CI (g)
+∆H -∆H
½CI2 (g) CI(g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
BaCI2 (s)
Ba2+ (g) + 2CI-
(g)
∆Hlatt
∆H form = - 860
Ba(s) + CI2 (g)
∆Hatom = + 175 Ba(s) → Ba(g)
Ba2+(g) + 2CI-
(g) ∆H i 1st/2nd = + 1500 Ba(g) → Ba2+
(g)
∆Hatom = + 121 x 2 ½CI2(g) → CI(g)
∆He 1st = - 354 x 2
CI(g) → CI -(g)
∆Hlatt = -2049
Ba2+ (g) + 2CI-
(g)
K+(g) + Br (g)
KBr (s)
K+(g) + Br (g)
K+(g) + ½Br2 (g)
K(g) + ½Br2 (g)
KBr (s)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally)
KBr (s)
∆H lattice = ????? ( Can’t be determined experimentally)
∆H form = - 392 ( Determined experimentally)
Ks) + ½Br2 (g)
Born Haber Cycle/BHC
K+(g) + Br–
(g) → KBr (s)
Find Lattice enthalpy for IONIC COMPOUND
Lattice Enthalpy +∆H (Heat absorb) to convert 1 MOL IONIC
compound to GASEOUS ions
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
KBr (s) → K+(g) + Br–
(g)
K (g) → K +(g) + e
Formation Enthalpy -∆H (Heat release) when 1 MOL compound form from its element under std condition
K(s) + ½Br2(g) → KBr(s)
Std Enthalpy Changes ∆Hθ needed for BHC
Ionization Enthalpy
1st Ionization enthalpy + ∆H when 1 MOL e removed
from 1 MOL atom in gaseous state
K K+ + e-
+
Electron affinity Enthalpy
+ e- -
Br- Br
Electron Affinity enthalpy -∆H when 1 MOL GASEOUS
atom gain 1 mol electron
CI (g) + e → CI -(g)
Gaseous state
Atomization Enthalpy
Atomization enthalpy + ∆H when 1 MOL GASEOUS atom form
from its element under STD condition
Formation Enthalpy
K Br2 KBr
½Br2 (g) → Br (g)
+∆H -∆H
½Br2 (g) Br (g)
Find Lattice enthalpy for IONIC COMPOUND using BHC
KBr (s)
K+ (g) + Br–
(g) K+ (g) + Br–
(g)
∆Hlatt
∆H form = - 392
K(s) + ½Br2 (g)
∆Hatom = + 89 K(s) → K(g)
K+(g) + Br-
(g) ∆Hie = + 420 K(g) → K+ (g)
∆Hatom = + 112 ½Br2(g) → Br(g)
∆He = - 342 CI(g) → CI -(g)
∆Hlatt = -671
∆H lattice
NaCI (s) NaCI (s)
Lattice Enthalpy
-∆H
Find Lattice enthalpy using BHC
2
21
r
qqkF
Theoretical Lattice Enthalpy (Calculated using formula)
Lattice enthalpy depend
Find Lattice enthalpy using Coulomb’s Law
Experimental/Actual Lattice Enthalpy (Calculated using BHC)
Assumption Ionic compound
Coulomb’s Law
CHARGE on ions
Electrostatic force
Electric charge (+) or (-)
Distance Coulomb constant
+ -
SIZE of ions
Size increase ↑ ↓
Separation bet ions increase ↑
Electrostatic force bet ion decrease ↓ ↓
Lattice enthalpy decrease ↓
Charge ↑ ↓
Electrostatic forces bet ion increases ↑ ↓
Lattice enthalpy increase ↑
Gp1 salt
Lattice Enthalpy kJ mol-1
LiCI + 846
NaCI + 771
KCI + 720
Size cation ↑
2
21
r
qqkF
Li
Na
K
Gp1 salt Lattice Enthalpy kJ mol-1
NaO + 2702
MgO + 3889
AI2O3 + 4020
CI
CI
CI
Charge cation ↑
Na+
Mg2+
AI3+
O
O
O
2
21
r
qqkF
Vs
Na+ (g) + CI–
(g)
∆H atom + ∆H ion + ∆H EA
( Determined experimentally)
∆H form = - 414 ( Determined experimentally)
Na+ (g) + CI–
(g) Electrostatic forces of attraction bet opposite charges
Vs Na(s) + ½CI2 (g)
Lattice Enthalpy
2
21
r
qqkF
Theoretical Lattice Enthalpy (Calculated using formula)
Lattice enthalpy depend
Find Lattice enthalpy using Coulomb’s Law
Assumption Ionic compound
Coulomb’s Law
CHARGE on ions
Electrostatic force
Electric charge (+) or (-)
Distance Coulomb constant
+ -
SIZE of ions
Size increase ↑ ↓
Separation bet ions increase ↑
Electrostatic force bet ion decrease ↓ ↓
Lattice enthalpy decrease ↓
Charge ↑ ↓
Electrostatic forces bet ion increases ↑ ↓
Lattice enthalpy increase ↑
Gp1 salt
Lattice Enthalpy kJ mol-1
LiCI + 846
NaCI + 771
KCI + 720
Size cation ↑
2
21
r
qqkF
Li
Na
K
Gp1 salt Lattice Enthalpy kJ mol-1
NaO + 2702
MgO + 3889
AI2O3 + 4020
CI
CI
CI
Charge cation ↑
Na+
Mg2+
AI3+
O
O
O
2
21
r
qqkF
Metal Halide
Lattice Enthalpy
F CI Br I
Li 1049 864 820 764
Na 930 790 754 705
K 830 720 691 650
Rb 795 695 668 632
Experimental/Actual Lattice Enthalpy (Calculated using BHC)
Size increase ↑ ↓
LE decrease ↓
Li
Na
K
Rb
F CI Br I Size increase ↑
↓ LE decrease ↓
Lattice Enthalpy
2
21
r
qqkF
Theoretical Lattice Enthalpy (Calculated using formula)
Find Lattice enthalpy using Coulomb’s Law
Assumption Ionic compound
Coulomb’s Law
Electrostatic force
Electric charge (+) or (-)
Distance Coulomb constant
Metal Halide
Lattice Enthalpy
F CI Br I
Li 1049 864 820 764
Na 930 790 754 705
K 830 720 691 650
Rb 795 695 668 632
Experimental/Actual Lattice Enthalpy (Calculated using BHC)
Li
Na
K
Rb
F CI Br I
Size increase ↑ ↓
LE decrease ↓
NaF NaCI NaBr NaI
Experimental
Lattice Enthalpy/(BHC) 930 776 740 700
Theoretical Lattice Enthalpy
910 769 732 682
AgF AgCI AgBr AgI
Experimental
Lattice Enthalpy/(BHC) 974 910 900 865
Theoretical Lattice Enthalpy
953 770 755 734
Uses of Born Haber Cycle – Determine degree of ionic /covalent character
High Difference in EN value
↓
High degree ionic character (100% ionic bond) ↓
Actual Expt LE (BHC) = Theoretical LE (Assume 100% ionic bond)
↓ Good agreement/Low % diff
Small Difference in EN value
↓
Ionic + Covalent character (NOT 100% ionic bond) ↓
Actual Expt LE (BHC) > Theoretical LE (Assume 100% ionic bond)
↓ Poor agreement/High % diff
Na – F Na - CI Na – Br Na - I
Diff in EN 3.1 2.1 1.9 1.6
Ag – F Ag - CI Ag – Br Ag - I
Diff in EN 2.1 1.1 0.9 0.6
NaF NaCI NaBr NaI
Experimental Lattice Enthalpy/(BHC)
930 776 740 700
Theoretical
Lattice Enthalpy 910 769 732 682
AgF AgCI AgBr AgI
Experimental Lattice Enthalpy/(BHC)
974 910 900 865
Theoretical Lattice Enthalpy
953 770 755 734
Uses of Born Haber Cycle – Determine degree of ionic /covalent character
High Difference in EN value
↓
High degree ionic character (100% ionic bond) ↓
Actual Expt LE (BHC) = Theoretical LE (Assume 100% ionic bond)
↓ Good agreement/Low % diff
↓
Small Difference in EN value
↓
Ionic + Covalent character (NOT 100% ionic bond) ↓
Actual Expt LE (BHC) > Theoretical LE (Assume 100% ionic bond)
↓ Poor agreement/High % diff
↓
Na – F Na - CI Na – Br Na - I
Diff in EN 3.1 2.1 1.9 1.6
Ag – F Ag - CI Ag – Br Ag - I
Diff in EN 2.1 1.1 0.9 0.6
Difference in electronegativity 0 0.4 2 4
difference < 0.4
covalent compound difference > 2
ionic compound
Diff = 2.5 – 2.1
= 0.4 Diff = 3 – 0.9
= 2.1
EN – 2.1 EN – 2.5
H C CI- Na+
EN - 3.0 EN - 0.9
Click here notes bonding triangle
Polar
covalent
Click here video bonding triangle
Polar covalent
Ionic
Bond
Ionic Bond
Due to high charge density cation (+) (charge/ionic radius) ↓ Donated electron cloud pull back to cation to form partial covalent bond ↓ Ionic + covalent character (Polar covalent)
Ag+ CI -
Electron cloud pull (covalent bond)
Polarization – cause polar covalent
No polarization (100% ionic)
NaF NaCI NaBr NaI
Experimental Lattice Enthalpy/(BHC)
930 776 740 700
Theoretical
Lattice Enthalpy 910 769 732 682
AgF AgCI AgBr AgI
Experimental Lattice Enthalpy/(BHC)
974 910 900 865
Theoretical Lattice Enthalpy
953 770 755 734
Uses of Born Haber Cycle – Determine degree of ionic /covalent character
High Difference in EN value
↓
High degree ionic character (100% ionic bond) ↓
Actual Expt LE (BHC) = Theoretical LE (Assume 100% ionic bond)
↓ Good agreement/Low % diff
↓
Small Difference in EN value
↓
Ionic + Covalent character (NOT 100% ionic bond) ↓
Actual Expt LE (BHC) > Theoretical LE (Assume 100% ionic bond)
↓ Poor agreement/High % diff
↓
Na – F Na - CI Na – Br Na - I
Diff in EN 3.1 2.1 1.9 1.6
Ag – F Ag - CI Ag – Br Ag - I
Diff in EN 2.1 1.1 0.9 0.6
Polar
covalent
Polar covalent
Ionic
Bond
Ionic Bond
Due to high charge density cation (+) (charge/ionic radius) ↓ Donated electron cloud pull back to cation to form partial covalent bond ↓ Ionic + covalent character (Polar covalent)
Ag+ CI -
Electron cloud pull (covalent bond)
Polarization – cause polar covalent
No polarization (100% ionic)
vs
Lattice enthalpy AgF – AgI > Lattice Enthalpy NaF – NaI ↓ ↓ Size Ag bigger > Size Na smaller ↓ ↓ LE Ag should be lower < LE Na should be higher ↓ ↓ Higher LE Ag due to > Lower LE Na due to ionic/covalent character only ionic character
Size increase ↑ ↓
LE decrease ↓
Ag+ CI - CI -
Electron cloud pull (covalent bond)
only ionic
BUT BUT
Born Haber Cycle/BHC
NaCI (s) → Na+(g) + CI–
(g)
-∆H
Lattice Enthalpy -∆H (Heat release) when 1 MOL IONIC compound form from GASEOUS ions
Find Lattice enthalpy using BHC
2
21
r
qqkF
Electrostatic forces of attraction bet opposite charges
Theoretical Lattice Enthalpy (Calculated using formula)
Find Lattice enthalpy using Coulomb’s Law
Experimental/Actual Lattice Enthalpy (Calculated using BHC)
Assume – 100% Ionic Coulomb’s Law
Lattice Enthalpy
Electrostatic force
Electric charge (+) or (-)
Distance Coulomb constant
+ - Na CI
Using Born Meyer eqn:
nner
qqAH
11
4
21
A = 1.747 q1 = +1 q2 = -1 n = 8 R = 283 x 10-12
4ƞe = 1.13 x 10 -10 r = Distance n = quantum #
Electric charge (+) or (-)
A = Madelung constant
Values for NaCI
∆Hlatt = 769
NaCI NaBr NaI
Experimental Lattice Enthalpy/(BHC)
776 740 700
Theoretical
Lattice Enthalpy (Calculated) 769 732 682
∆Hlatt = 776
Theoretical LE (Assume 100% ionic bond) = Expt LE (BHC)