IB Chemistry on Arrhenius, Bronsted Lowry Conjugate Acid Base Pair and Lewis Acid

Brønsted-Lowry Acid - substance that donate proton/proton donorBronsted-Lowry Base – substance that accept proton/proton acceptorOne species donate proton – one species accept proton

Arrhenius acid - substance dissociate in water produce H+ ion.Arrhenius base – substance dissociate in water produce OH- ion.All Arrhenius acid are Bronsted Lowry acid and water must be present

HCI → H+ + CI-

HCI + H2O ↔ H3O+ + CI-

NaOH→ Na+ + OH-

NH3 + H2O ↔ NH4+ + OH-

CO32- + H2O ↔ HCO3

- + OH-

Water/aqueous medium

Water/aqueous mediumOther solvent medium possible

Definition of Acid and Bases

Arrhenius acid Arrhenius base H+ OH-

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gain H+

Acid + Base ↔ Conjugate Base + Conjugate Acid

lose H+

HCI (acid) - CI- (conjugate base)

lose H+

H2O (base) - H3O+ (conjugate acid)

HCI + H2O ↔ CI- + H3O+

gain H+

Lewis Acid - substance that accept electron/electron acceptor, empty orbital/electron deficientLewis Base – substance that donate electron/electron donor, lone pair electronLewis Base - donate electron pair forming dative/coordinate bond with Lewis acid

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HCI + H2O → CI- + H3O+

H2O donate e-HCI accept e-

Lewis acid Lewis base

Conjugate acid base pair differ by one proton

Bronsted Base Bronsted Base

Bronsted Base Bronsted Base


Arrhenius acid - substance dissociate in water to produce H+ ions.Arrhenius base – substance dissociate in water to produce OH- ions.All Arrhenius acid are Bronsted Lowry acid and water must be present

HCI → H+ + CI-


NaOH→ Na+ + OH-

NH3 + H2O ↔ NH4+ + OH-

CO32- + H2O ↔ HCO3

- + OH-



Acid and Bases


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Bronsted Base

HPO42- + SO3

2- ↔ PO43- + HSO3

- HCOOH + CN- ↔ HCOO- + HCN


NH4+ + CO2

2- ↔ NH3 + HCO3- CH3COOH + H2O ↔ H3O+ + CH3COO-

Brønsted Acid Brønsted Acid



Brønsted Acid

Brønsted Acid

Bronsted Base

HF + H2O ↔ F- + H3O+

Bronsted Base

H2PO4- + OH- ↔ HPO4

2- + H2O

Bronsted Base

H2SO4 + N2H5+ ↔ HSO4

- + N2H62+

Brønsted Acid

Bronsted Base

HCO3- + H2O ↔ CO3

2- + H3O+

Brønsted-Lowry Acid - proton donor - Bronsted-Lowry Base – proton acceptorEvery acid has a conjugate base - Every base has a conjugate acidAcid donate proton – Base accept protonConjugate acid has one more H than base - Conjugate base has one fewer H than acid.

Bronsted Lowry Conjugate acid base pair



HCI (acid) - CI- (conjugate base)

CH3COOH + H2O ↔ CH3COO- + H3O+


CH3COOH (acid) - CH3COO- (conjugate base)

HF + H2O ↔ F- + H3O+


HF (acid) - F- (conjugate base)

H2SO4 + N2H5+ ↔ HSO4

- +N2H62+

H2SO4 (acid) - HSO4- (conjugate base)

N2H5+ (base) - N2H6

2+(conjugate acid)

HCOOH (acid) - HCOO- (conjugate base)

HCOOH + CN- ↔ HCOO- + HCN

CN- (base) – HCN (conjugate acid)

HPO42- + SO3

2- ↔ PO43- + HSO3

-

HPO42- (acid) - PO4

3- (conjugate base)

SO32- (base) - HSO3

- (conjugate acid)

CONJUGATE

ACID

BASE

gain H+

lose H+

gain H+

lose H+

gain H+

lose H+

gain H+

lose H+

gain H+

lose H+

gain H+

lose H+

gain H+

lose H+



HCOOH (acid) - HCOO- (conjugate base)

HCOOH + CN- ↔ HCOO- + HCN HPO42- + SO3

2- ↔ PO43- + HSO3

-

HPO42- (acid) - PO4

3- (conjugate base)

SO32- (base) - HSO3

- (conjugate acid)

NH3 + H2O ↔ NH4+ + OH-

H2O (acid) - OH- (conjugate base)

NH3 (base) - NH4+ (conjugate acid)

NH4+ + CO2

2-↔ NH3 + HCO3-

NH4+ (acid) - NH3 (conjugate base)

CO22- (base) - HCO3

- (conjugate acid)

NH3 + H2S ↔ NH4+ + HS- H2PO4

- + OH- ↔ HPO42- + H2O

H2PO4- (acid) - HPO4

2- (conjugate base)

OH- (base) - H2O (conjugate acid)

NH3 (base) - NH4+ (conjugate acid)

H2S (acid) - HS- (conjugate base)

CONJUGATE

ACID

BASE

Brønsted-Lowry Acid - proton donor - Bronsted-Lowry Base – proton acceptorEvery acid has a conjugate base - Every base has a conjugate acidConjugate acid has one more H than base - Conjugate base has one fewer H than acid.

gain H+

lose H+

lose H+

gain H+

CN-(base) - HCN (conjugate acid)

gain H+

lose H+

lose H+gain H+

lose H+

gain H+

lose H+

gain H+


CH3COOH ↔ CH3COO-

H2O ↔ H3O+

Conjugate acid base pair

Conjugate acid base pair

CH3COOH CH3COO-

H2O H3O+Conjugate acid

Conjugate baseAcid

Base

Strong Acid form → Weak Conjugate Base• Strong acid HCI dissociate completely to form Cl− (weak conjugate base)• Cl− weak conjugate base won't accept H+ to form back HCI• HCI + H2O → Cl− + H3O+ (one way)


lose H+

gain H+



Strong acid (HCI) form

weak conjugate base (CI-)

Weak conjugate base (CI) will not accept H+ to form back HCI

Weak Acid form ↔ Strong Conjugate Base• CH3COOH weak acid dissociate partially, form CH3COO- (strong conjugate base)• CH3COO- (strong conjugate base) accept H+ to form back CH3COOH molecule.• CH3COOH + H2O ↔ CH3COO- + H3O+ (reversible)

Weak acid (CH3COOH) form

strong conjugate base (CH3COO-)

Strong conjugate base (CH3COO-) accept H+ form back CH3COOH


lose H+

gain H+



Strong base (NaOH) form

weak conjugate acid (H2O)

Weak conjugate acid (H2O) will not lose H+ to form back OH-

Weak base (NH3) form

strong conjugate acid (NH4+)

Strong conjugate acid (NH4) lose H+ to form back NH3

Strong Base form → Weak Conjugate acid• Strong base NaOH dissociate completely to form OH-

• OH- strong base dissolve in water form H2O (weak conjugate acid) • H2O (weak conjugate acid ) will not lose H+ to form back OH-

• OH- + H2O → H2O + OH- ( one way)

Weak Base form ↔ Strong Conjugate AcidNH3 weak base dissociate partially to form NH4

+ (strong conjugate acid)NH3 + H2O ↔ NH4

+ + OH-

NH4+ (strong conjugate acid) lose H+ to form back NH3

NH3 + H2O ↔ NH4+ + OH- (reversible)

Conjugate Acid

Conjugate Base

H2SO4 HSO4

HCI CI-

H2SO3 HSO3-

HF F-

HNO2 NO2-

CH3COOH CH3COO-

Conjugate Base

Conjugate Acid

OH- H2O

PO43- HPO4

2-

CO32- HCO3

-

NH3 NH4+


Strong Base + Acid ↔ Weak Conjugate Acid + Conjugate Base

Strong acid

Weak acid

Weak conjugate base

Strong conjugate base

Strong base

Weak baseStrong conjugate acid

Weak conjugate acid

Strong Acid + Base ↔ Weak Conjugate Base + Conjugate Acid

Weak Acid + Base ↔ Strong Conjugate Base + Conjugate Acid

Weak Base + Acid ↔ Strong Conjugate Acid + Conjugate Base

reversible

reversible

one way

one way

reversible

reversible

reversible

H2O (amphiprotic) - act as acid or base

H2O + HCI ↔ H3O+ + CI-

HCO3- – Base, proton acceptor

HSO4- – Base, proton acceptor

Bronsted Lowry Conjugate Acid base pair

H2O – Acid, proton donor H2O – Base, proton acceptor

HCO3- (amphiprotic) - act as acid or base

HCO3- – Acid, proton donor

H2O + NH3 ↔ NH4+ + OH-

HCO3- + OH- ↔ CO3

2- + H2O HCO3- + H3O+ ↔ H2CO3 + H2O

HSO4- (amphiprotic) - act as acid or base

HSO4- – Acid, proton donor

HSO4- + H2O ↔ H3O+ + SO4

2- HSO4- + HCI ↔ H2SO4 + CI-

Amphiprotic substance :• Act as acid or base • Involve only H+.

• Able to donate H+ or gain H+ ions• All amphiprotic are amphoteric

Amphoteric substance:• Act as acid or base• Does not involve only H+ ions• Al2O3 is amphoteric – No H+ ions• Al2O3 (base) + 6HCI → 2AICI3 + 3H2O

• AI2O3 (acid) + 2NaOH + 3H2O → 2NaAl(OH)4

amphiprotic

amphoteric

gain H+lose H+

lose H+

lose H+

gain H+

gain H+

H+

Amphiprotic – Proton donor (acid)- Proton acceptor (base)

SO2 accept e- CO2 accept e-


CO2 + H2O → H2CO3

H2O donate e-


H2O donate e-

Lewis Acid/Base

Lewis Acid - substance accept electron/electron acceptor, empty orbital/electron deficientLewis Base – substance donate electron/lone pair electron donor

Lewis acid – electrophileLewis base - nucleophileDonation/acceptance electron pair

Lewis Acid Lewis Base

LIKE electron (-ve)Electron deficient – accept lone pair

LIKE nucleus (+ve)Electron rich – donate lone pair

NO2+ Br+SO2 CO2

SO2 + H2O → H2SO3

Molecule asLewis Acid/Base

Molecule acting as Lewis Acid Molecule /Ions as Lewis Base

Lewis Acid/Base

H2O donate e-

HCI + :H2O → CI- + H3O+

HCI accept e-


BF3 + :NH3 → BF3 – NH3



HF accept e-

Lewis acid

HF + H2O → F- + H3O+

H2O donate e-

Lewis baseLewis acid

Lewis Acid - substance accept electron/electron acceptor, empty orbital/electron deficientLewis Base – substance donate electron/lone pair electron donorLewis Base - donate electron pair form dative/coordinate bond with Lewis acid


H+ transferDative bond

Dative bond

Dative bond

Electrondonor

Electronacceptor

Electronacceptor

Electrondonor

Electron AcceptorElectron Deficient

Electron donorElectron donorElectron Acceptor

Electron Deficient

NH3 donate e-

BF3 accept e-

F F-

No H+ transfer

BF3 + :F → BF4

F donate e-BF3 accept e-

:F :F

Dative bondLewis base

SO2 + H2O → H2SO3

SO2 accept e- CO2 accept e-Molecule asLewis Acid/Base



H2O + :O2- → 2OH-

O2- donate e-

H2O accept e-


CH3COOH accept e-

CO2 + H2O → H2CO3

H2O donate e-


H2O donate e-


H2O donate e-

Lewis Acid/Base





Ligand as Lewis Base• lone pair electron

• dative bond with metal

Lewis Acid/Base



Lewis Acid Lewis Base

LIKE electron (-ve)Electron deficient – accept lone pair

LIKE nucleus (+ve)Electron rich – donate lone pair

Cu2+

Metal Ion as Lewis Acid•high charge density• empty 3d orbitals

Ni2+ AI3+ Fe3+

Cu2+ + :6H2O → [Cu(H2O)6]2+

Cu2+ accept e-Metal Ion as Lewis Acid

Ligand as Lewis BaseH2O donate e-

Lewis acid

Co2+ + :4CI- → [Co(CI)4]2-

CI- donate e-

Lewis base Lewis acid Lewis base

C02+ accept e-

Co2+

Metal Ion as Lewis AcidLigand as Lewis Base


Fe3+ + :SCN- → [FeSCN]2+

SCN- donate e-

Fe3+ accept e-

H2O donate e-

Fe3+ + 6H2O → [Fe(H2O)]3+


Fe3+ accept e-

AI(OH)3 + :OH- → AI(OH)4-

OH- donate e-

AI3+ accept e-


Ni2+ + :6NH3 → [Ni(NH3)6]2+

NH3 donate e-

Ni2+ accept e-


Lewis Acid/Base

Metal Ion as Lewis AcidLigand as Lewis Base

Lewis Acid - substance accept electron/electron acceptor, empty orbital/electron deficientLewis Base – substance donate electron/lone pair electron donorLewis Base - donate electron pair form dative/coordinate bond with Lewis acid



Arrhenius acid - substance dissociate in water to produce H+ ions.Arrhenius base – substance dissociate in water to produce OH- ions.All Arrhenius acid are Bronsted Lowry acid and water must be present

HCI → H+ + CI-


NaOH→ Na+ + OH-

NH3 + H2O ↔ NH4+ + OH-

CO32- + H2O ↔ HCO3

- + OH-





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gain H+


lose H+HCI (acid) - CI- (conjugate base)



Lewis Acid - accept electron/electron acceptor, empty orbital/electron deficientLewis Base – donate electron/lone pair electron donor.Lewis Base - donate electron pair form dative/coordinate bond with Lewis acid

3

HCI + H2O → CI- + H3O+

H2O donate e-HCI accept e-


gain H+

lose H+

Metal Ion as Lewis Acid• electron acceptor• high charge density• empty 3d orbitals

Ligand as Lewis Base• electron donor • lone pair electron • dative bond with metal


For following species, state whether it behave as Lewis acid or Lewis base

a) PH3

b) BCI3

c) H2Sd) SF4

e) Cu2+

a) PH3 – P (gp 5) - 1 lone pair electron – electron donor – Lewis baseb) BCI3 – B (gp 3) - electron deficient/incomplete valence shell – electron acceptor – Lewis acidc) H2S – S (gp 6) - 2 lone pair electron – electron donor – Lewis based) SF4 – S (gp 6) - 1 lone pair electron – electron donor – Lewis basee) Cu2+ - (transition metal) – high charge density/incomplete 3d orbital – electron acceptor – Lewis acid

Question Answer

IB Questions

Which acid/base rxn is Lewis Theory and Bronsted Theory?A) NH3 + HCI ↔ NH4CI B) H2O + H2O ↔ H3O

+ + OH- C) Cu2+ + 4NH3 ↔ [Cu(NH3)4]2+ D) BaO + H2O ↔ Ba2+ + 2OH-

A) NH3 + HCI ↔ NH4CI B) H2O + H2O ↔ H3O+ + OH- C) Cu2+ + 4NH3 ↔ [Cu(NH3)4]

2+ D) O2- + H2O ↔ 2OH-

Bronsted Theory Bronsted Theory Lewis Theory Bronsted Theory(H+ transfer) (H+ transfer) (NO H+ transfer) (H+ transfer)

H+H+ H+

Identify Lewis acid and Lewis base

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A) Zn2+ + 4NH3 → [Zn(NH3 )4 ] 2+ B) 2CI - + BeCI2 → [BeCI4]2- C) Mg2+ + 6H2O → [Mg(H2O)6]

2+

Lewis acidLewis acid

Lewis acid

Lewis base Lewis base

Lewis base

Lewis Acid/Base


Bronsted – Lowry

Acid/Base

Arrhenius Acid/Base

Arrhenius acid/base• Limited/narrow definition• Only water medium• Substance must have H atom

Bronsted Lowry acid/base• Broader definition • Proton donor/acceptor• Other medium• Substance must have H atom

Lewis acid/base• Broadest definition• Electron acceptor/donor• Substance doesn’t need to have H

All Arrhenius acid are Bronsted Lowry acid All Bronsted Lowry acid are Lewis acid

Click here Bronsted Lowry , Lewis Acid/Base

Video on Acid/ Base

Click here on Lewis Acid/Base

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IB Chemistry on Arrhenius, Bronsted Lowry Conjugate Acid Base Pair and Lewis Acid

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