Brønsted-Lowry Acid - substance that donates proton/proton donor Bronsted-Lowry Base – substance that accepts proton/proton acceptor One species donate proton – one species accept proton Arrhenius acid - substance dissociates in water to produce H + ions. Arrhenius base – substance dissociates in water to produce OH - ions. All Arrhenius acid are Bronsted Lowry acid and water must be present HCI ↔ H + + CI - HCI + H 2 O ↔ H 3 O + + CI - NaOH → Na + + OH - NH 3 + H 2 O ↔ NH 4 + + OH - CO 3 2- + H 2 O ↔ HCO 3 - + OH - Water/aqueous medium Water/aqueous medium Other solvent medium possible Involve H atoms Definition of Acid and Bases http://4photos.net/en/image:44-225901-Water_droplets_on_blue_backdrop__images Arrhenius acid Arrhenius base H + OH - 2 1 gain H Acid + Base ↔ Conjugate Base + Conjugate Acid lose H HCI (acid) - CI - (conjugate base) lose H H 2 O (base) - H 3 O + (conjugate acid) HCI + H 2 O ↔ CI - + H 3 O + gain H Lewis Acid - substance that accepts electron/electron acceptor, empty orbital/electron deficient Lewis Base – substance that donates electron/electron donor, lone pair electron Lewis Base - donate electron forming dative/coordinate bond with Lewis acid 3 HCI + H 2 O → CI - + H 3 O + H 2 O donate e- HCI accept e- Lewis acid Lewis base
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IB Chemistry on Arrhenius, Bronsted Lowry Conjugate Acid Base Pair and Lewis Acid.
IB Chemistry on Arrhenius, Bronsted Lowry Conjugate Acid Base Pair and Lewis Acid.
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Brønsted-Lowry Acid - substance that donates proton/proton donor Bronsted-Lowry Base – substance that accepts proton/proton acceptor One species donate proton – one species accept proton
Arrhenius acid - substance dissociates in water to produce H+ ions. Arrhenius base – substance dissociates in water to produce OH- ions. 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 medium Other solvent medium possible Involve H atoms
Lewis Acid - substance that accepts electron/electron acceptor, empty orbital/electron deficient Lewis Base – substance that donates electron/electron donor, lone pair electron Lewis Base - donate electron 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
Bronsted Base Bronsted Base
Bronsted Base Bronsted Base
Brønsted-Lowry Acid - substance that donates proton/proton donor Bronsted-Lowry Base – substance that accepts proton/proton acceptor One species donate proton – one species accept proton
Arrhenius acid - substance dissociates in water to produce H+ ions. Arrhenius base – substance dissociates in water to produce OH- ions. 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 medium Other solvent medium possible
Brønsted-Lowry Acid - proton donor - Bronsted-Lowry Base – proton acceptor Every acid has a conjugate base - Every base has a conjugate acid Acid donate proton – Base accept proton Conjugate acid has one more H than base - Conjugate base has one fewer H than acid.
Bronsted Lowry Conjugate acid base pair
Acid + Base ↔ Conjugate Base + Conjugate Acid
HCI + H2O ↔ CI- + H3O+
H2O (base) - H3O+ (conjugate acid)
HCI (acid) - CI- (conjugate base)
CH3COOH + H2O ↔ CH3COO- + H3O+
H2O (base) - H3O+ (conjugate acid)
CH3COOH (acid) - CH3COO- (conjugate base)
HF + H2O ↔ F- + H3O+
H2O (base) - H3O+ (conjugate acid)
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)
C O N J U G A T E A C I D B A S E
lose H
lose H
lose H
lose H
lose H
lose H
gain H gain H
gain H gain H
gain H gain H
gain H
lose H
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Bronsted Lowry Conjugate acid base pair
Acid + Base ↔ Conjugate Base + 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)
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)
C O N J U G A T E A C I D B A S E
lose H
lose H
lose H
lose H
lose H
lose H
lose H
gain H
gain H
gain H
gain H
gain H
gain H gain H
Brønsted-Lowry Acid - proton donor - Bronsted-Lowry Base – proton acceptor Every acid has a conjugate base - Every base has a conjugate acid Acid donate proton – Base accept proton Conjugate acid has one more H than base - Conjugate base has one fewer H than acid.
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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 )
Bronsted Lowry Conjugate acid base pair
lose H
gain H
Acid + Base ↔ Conjugate Base + Conjugate Acid
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 to form CH3COO- (strong conjugate base) • CH3COO- (strong conjugate base) will 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+ to form back CH3COOH
Brønsted-Lowry Acid - proton donor - Bronsted-Lowry Base – proton acceptor Every acid has a conjugate base - Every base has a conjugate acid Acid donate proton – Base accept proton Conjugate acid has one more H than base - Conjugate base has one fewer H than acid.
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Bronsted Lowry Conjugate acid base pair
lose H
gain H
Acid + Base ↔ Conjugate Base + Conjugate Acid
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 to form H2O (weak conjugate acid) • OH- + H2O → H2O + OH- ( one way) • H2O (weak conjugate acid ) will not lose H+ to form back OH-
Weak Base form Strong Conjugate Acid NH3 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)
Brønsted-Lowry Acid - proton donor - Bronsted-Lowry Base – proton acceptor Every acid has a conjugate base - Every base has a conjugate acid Acid donate proton – Base accept proton Conjugate acid has one more H than base - Conjugate base has one fewer H than acid.
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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+
Bronsted Lowry Conjugate acid base pair
Strong Base + Acid → Weak Conjugate Acid + Conjugate Base
Strong acid
Weak acid
Weak conjugate base
Strong conjugate base
Strong base
Weak base Strong 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
• Act as acid or base • All amphiprotic are amphoteric
Amphoteric substance: • Act as acid or base • Does not involve only H+ ions • Al2O3 is amphoteric – have no H+ ions • Al2O3(base) + 6HCI → 2AICI3 + 3H2O • AI2O3(acid) + 2NaOH + 3H2O → 2NaAl(OH)4
amphiprotic
amphoteric
Lewis Acid/Base
HCI + H2O → CI- + H3O+
HCI accept e-
Lewis acid Lewis base
BF3 + NH3 → BF3 – NH3
BF3 accept e-
NH3 donate e-
Molecule acting as Lewis Acid/Base
Lewis acid Lewis base
HF accept e-
CN- donate e-
Lewis acid Lewis base
HCOOH accept e-
HF + H2O ↔ F- + H3O+
H2O donate e-
F
Lewis base Lewis acid
F
HCOOH + :CN- ↔ HCOO- + HCN
Lewis Acid - substance that accepts electron/electron acceptor, empty orbital/electron deficient Lewis Base – substance that donates electron/electron donor, lone pair electron Lewis Base - donate electron pair forming dative/coordinate bond with Lewis acid
H2O donate e-
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SO2 + H2O → H2SO3
SO2 accept e- CO2 accept e-
Molecule acting as Lewis Acid/Base
Lewis acid Lewis base
Lewis base Lewis acid
H2O + :O2- → 2OH-
O2- donate e-
H2O accept e-
Lewis acid Lewis base
CH3COOH accept e-
CO2 + H2O → H2CO3
H2O donate e-
Lewis acid Lewis base
H2O donate e-
CH3COOH + H2O ↔ CH3COO- + H3O+
H2O donate e-
Lewis Acid/Base
Lewis Acid - substance that accepts electron/electron acceptor, empty orbital/electron deficient Lewis Base – substance that donates electron/electron donor, lone pair electron Lewis Base - donate electron pair forming dative/coordinate bond with Lewis acid
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Metal Ion as Lewis Acid Ligand as Lewis Base
Lewis base Lewis acid
Fe3+ + :SCN- → [FeSCN]2+
SCN- donate e-
Fe3+ accept e-
H2O donate e-
Fe3+ + 6H2O → [Fe(H2O)]3+
Lewis acid Lewis base
Fe3+ accept e-
AI(OH)3 + OH- → AI(OH)4
-
OH- donate e-
AI3+ accept e-
Lewis base Lewis acid
Ni2+ + :6NH3 → [Ni(NH3)6]2+
NH3 donate e-
Ni2+ accept e-
Lewis base Lewis acid
Lewis Acid/Base
Lewis Acid - substance that accepts electron/electron acceptor, empty orbital/electron deficient Lewis Base – substance that donates electron/electron donor, lone pair electron Lewis Base - donate electron pair forming dative/coordinate bond with Lewis acid
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Metal Ion as Lewis Acid Ligand as Lewis Base
Lewis base Lewis acid
Fe3+ + :SCN- → [FeSCN]2+
SCN donate e-
Fe3+ accept e-
H2O donate e-
Fe3+ + 6H2O → [Fe(H2O)]3+
Lewis acid Lewis base
Fe3+ accept e-
Metal Ion as Lewis Acid • electron acceptor • high charge density • empty 3d orbitals • attract ligands
Ligand as Lewis Base • electron donor • lone electron pair • dative bond with metal
For following species, state whether it behave as Lewis acid or Lewis base
a) PH3
b) BCI3
c) H2S d) SF4
e) Cu2+
a) PH3 – P (gp 5) - 1 lone pair electron – electron donor – Lewis base b) BCI3 – B (gp 3) - electron deficient/incomplete valence shell – electron acceptor – Lewis acid c) H2S – S (gp 6) - 2 lone pair electron – electron donor – Lewis base d) SF4 – S (gp 6) - 1 lone pair electron – electron donor – Lewis base e) Cu2+ - (transition metal) – high charge density/incomplete 3d orbital – electron acceptor – Lewis acid
Lewis Acid/Base
Lewis Acid - substance that accepts electron/electron acceptor, empty orbital/electron deficient Lewis Base – substance that donates electron/electron donor, lone pair electron Lewis Base - donate electron pair forming dative/coordinate bond with Lewis acid
Question Answer
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Brønsted-Lowry Acid - substance that donates proton/proton donor Bronsted-Lowry Base – substance that accepts proton/proton acceptor One species donate proton – one species accept proton
Arrhenius acid - substance dissociates in water to produce H+ ions. Arrhenius base – substance dissociates in water to produce OH- ions. 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 medium Other solvent medium possible Involve H atoms
Lewis Acid - substance that accepts electron/electron acceptor, empty orbital/electron deficient Lewis Base – substance that donates electron/electron donor, lone pair electron Lewis Base - donate electron forming dative/coordinate bond with Lewis acid
3
HCI + H2O → CI- + H3O+
H2O donate e- HCI accept e-
Lewis acid Lewis base
Lewis Acid/Base
Definition of Acid and Bases
Bronsted – Lowry
Acid/Base
Arrhenius Acid/Base
Arrhenius acid/base • too limit/narrow definition • only water medium • substance must have H atoms
Bronsted Lowry acid/base • broader definition • proton donor/acceptor • other solvent medium • substance must have H atoms
Lewis acid/base • broader definition • electron acceptor/donor • doesn’t need to have H atoms
All Arrhenius acid are Bronsted Lowry acid and all Bronsted Lowry acid are Lewis acid
Click here on pH calculation Click here on Bronsted Lowry and Lewis Acid/Base