Acid-Base theoriesAcid-Base theoriesAcid-Base theoriesAcid-Base theoriesAn IntroductionAn Introduction
Properties of acids and basesProperties of acids and bases
Acids:
Taste sour or tart
React with some metals to produce H2(g)
Turn litmus paper red
Can be strong (HCl) or weak (CH3COOH)
Acids:
Taste sour or tart
React with some metals to produce H2(g)
Turn litmus paper red
Can be strong (HCl) or weak (CH3COOH)
Properties of acids and basesProperties of acids and bases
Common Acids:
HCl: hydrochloric acid
HNO3: nitric acid
H2SO4: sulfuric acid
H3PO4: phosphoric acid
CH3COOH: acetic (ethanoic) acid
H2CO3: carbonic acid
Common Acids:
HCl: hydrochloric acid
HNO3: nitric acid
H2SO4: sulfuric acid
H3PO4: phosphoric acid
CH3COOH: acetic (ethanoic) acid
H2CO3: carbonic acid
Properties of acids and basesProperties of acids and bases
Bases:
Taste bitter
Feel slippery
Turn litmus paper blue
Can be strong (NaOH) or weak (NH3)
Bases:
Taste bitter
Feel slippery
Turn litmus paper blue
Can be strong (NaOH) or weak (NH3)
Properties of acids and basesProperties of acids and bases
Common Bases:
KOH: potassium hydroxide
NaOH: sodium hydroxide
Ca(OH)2: calcium hydroxide
Mg(OH)2: magnesium hydroxide
Common Bases:
KOH: potassium hydroxide
NaOH: sodium hydroxide
Ca(OH)2: calcium hydroxide
Mg(OH)2: magnesium hydroxide
TheoriesTheories
Acid-Base theories try to explain the actions of acids and bases.
Acids and bases play such a very important role in general and biochemistry that we need a good theory to help us understand the reactions.
In addition, with a good theory, we should be able to predict the products of unknown but related reactions.
Acid-Base theories try to explain the actions of acids and bases.
Acids and bases play such a very important role in general and biochemistry that we need a good theory to help us understand the reactions.
In addition, with a good theory, we should be able to predict the products of unknown but related reactions.
TheoriesTheories
All theories deal with strong and weak acids and bases.
Strong acids and bases are fully dissociated in solution.
HCl(g) → H+(aq) + Cl-(aq)
NaOH(s) → Na+(aq) + OH-(aq)
The reactions go to completion.
There are no reactants present in the solution.
All theories deal with strong and weak acids and bases.
Strong acids and bases are fully dissociated in solution.
HCl(g) → H+(aq) + Cl-(aq)
NaOH(s) → Na+(aq) + OH-(aq)
The reactions go to completion.
There are no reactants present in the solution.
TheoriesTheories
Strong acids (these are all of them):
HCl hydrochloric acid
HBr hydrobromic acid
HI hydroiodic acid
HNO3 nitric acid
HClO3 chloric acid
H2SO4 sulfuric acid
Strong acids (these are all of them):
HCl hydrochloric acid
HBr hydrobromic acid
HI hydroiodic acid
HNO3 nitric acid
HClO3 chloric acid
H2SO4 sulfuric acid
TheoriesTheories
Strong bases:
all metal hydroxides, such as
NaOH sodium hydroxide
KOH potassium hydroxide
Ca(OH)2 calcium hydroxide
Strong bases:
all metal hydroxides, such as
NaOH sodium hydroxide
KOH potassium hydroxide
Ca(OH)2 calcium hydroxide
TheoriesTheories
Weak acids and bases are only partially dissociated.
There is an equilibrium when the rate of product formation equals the rate of reactant formation.
CH3COOH(aq) + H2O(l) ⇌ H3O+(aq) + CH3COO-
(aq)
NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)
Both reactants and products remain in solution.
Weak acids and bases are only partially dissociated.
There is an equilibrium when the rate of product formation equals the rate of reactant formation.
CH3COOH(aq) + H2O(l) ⇌ H3O+(aq) + CH3COO-
(aq)
NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)
Both reactants and products remain in solution.
TheoriesTheories
Weak acids:
any acid not a strong acid, such as
H3PO4 phosphoric acid
CH3COOH acetic acid
HF hydrofluoric acid
Weak acids:
any acid not a strong acid, such as
H3PO4 phosphoric acid
CH3COOH acetic acid
HF hydrofluoric acid
TheoriesTheories
Weak bases:
any base that is not a metal hydroxide, such as
NH3 ammonia
CH3NH2 methylamine
CH3CH2NH2 ethylamine
and other nitrogen containing organic compounds
Weak bases:
any base that is not a metal hydroxide, such as
NH3 ammonia
CH3NH2 methylamine
CH3CH2NH2 ethylamine
and other nitrogen containing organic compounds
Arrhenius acids and basesArrhenius acids and bases
Arrhenius acids are
H+ containing compounds
increase the H+ concentration in water
Typical reactions:
H-Cl(g) → H+(aq) + Cl-(aq)
H-Cl(g) + H2O(l)→ H3O+(aq) + Cl-(aq)
Arrhenius acids are
H+ containing compounds
increase the H+ concentration in water
Typical reactions:
H-Cl(g) → H+(aq) + Cl-(aq)
H-Cl(g) + H2O(l)→ H3O+(aq) + Cl-(aq)
hydronium ionhydronium ion
Arrhenius acids and basesArrhenius acids and bases
Arrhenius bases are
OH- containing compounds
increase the OH- concentration in water
Typical Reactions:
NaOH(s) → Na+(aq) + OH-(aq)
KOH(s) → K+(aq) + OH-(aq)
Arrhenius bases are
OH- containing compounds
increase the OH- concentration in water
Typical Reactions:
NaOH(s) → Na+(aq) + OH-(aq)
KOH(s) → K+(aq) + OH-(aq)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Brønsted-Lowry acids are
H+ donors
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
Brønsted-Lowry bases are
H+ acceptors
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
Brønsted-Lowry acids are
H+ donors
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
Brønsted-Lowry bases are
H+ acceptors
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Conjugate acids and bases:
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
In this reaction
HCl is the H+ donor (acid)
H2O is the H+ acceptor (base)
Conjugate acids and bases:
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
In this reaction
HCl is the H+ donor (acid)
H2O is the H+ acceptor (base)
(acid)(acid) (base)(base)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Conjugate acids and bases:
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
In the reverse reaction
Conjugate acids and bases:
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
In the reverse reaction
H3O+ is the H+ donor (acid)
Cl- is the H+ acceptor (base)
H3O+ is the H+ donor (acid)
Cl- is the H+ acceptor (base)
(acid)(acid) (base)(base) (base)(base) (acid)(acid)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Conjugate acids and bases:
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
Conjugate acids and bases:
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
HCl is an acid
Cl- is a base
HCl and Cl- are conjugate acid and base.
HCl is an acid
Cl- is a base
HCl and Cl- are conjugate acid and base.
(acid)(acid) (base)(base) (base)(base) (acid)(acid)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Conjugate acids and bases:
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
Conjugate acids and bases:
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
H3O+ is an acid
H2O is a base
H3O+ and H2O are conjugate acid and base.
H3O+ is an acid
H2O is a base
H3O+ and H2O are conjugate acid and base.
(acid)(acid) (base)(base) (base)(base) (acid)(acid)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Conjugate acids and bases:
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
In this reaction
H2O is the H+ donor (acid)
NH3 is the H+ acceptor (base)
Conjugate acids and bases:
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
In this reaction
H2O is the H+ donor (acid)
NH3 is the H+ acceptor (base)
(base)(base) (acid)(acid)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Conjugate acids and bases:
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
In the reverse reaction
Conjugate acids and bases:
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
In the reverse reaction
NH4+ is the H+ donor (acid)
OH- is the H+ acceptor (base)
NH4+ is the H+ donor (acid)
OH- is the H+ acceptor (base)
(base)(base) (acid)(acid) (acid)(acid) (base)(base)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Conjugate acids and bases:
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
Conjugate acids and bases:
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
NH3 is a base
NH4+ is an acid
NH3 and NH4+ are conjugate acid and base.
NH3 is a base
NH4+ is an acid
NH3 and NH4+ are conjugate acid and base.
(base)(base) (acid)(acid) (acid)(acid) (base)(base)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Conjugate acids and bases:
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
Conjugate acids and bases:
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
H2O is an acid
OH- is a base
H2O and OH- are conjugate acid and base.
H2O is an acid
OH- is a base
H2O and OH- are conjugate acid and base.
(base)(base) (acid)(acid) (acid)(acid) (base)(base)
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
Notice that in the reaction
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
H2O acts as a base
and in the reaction
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
H2O acts as an acid
Notice that in the reaction
HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq)
H2O acts as a base
and in the reaction
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
H2O acts as an acid
Brønsted-Lowry acids and basesBrønsted-Lowry acids and bases
The behavior of water to act as a base or as an acid is called amphoterism.
Water is amphoteric.
Other species can also be amphoteric:
HSO4- (hydrogen sulfate ion)
HCO3- (hydrogen carbonate ion)
H2PO4- (dihydrogen phosphate ion)
The behavior of water to act as a base or as an acid is called amphoterism.
Water is amphoteric.
Other species can also be amphoteric:
HSO4- (hydrogen sulfate ion)
HCO3- (hydrogen carbonate ion)
H2PO4- (dihydrogen phosphate ion)
Lewis acids and basesLewis acids and bases
Lewis acid:
e- pair acceptor
H+ (the H is e- poor)
Lewis base:
e- pair donor
O−H- (the O is e- rich)
Lewis acid:
e- pair acceptor
H+ (the H is e- poor)
Lewis base:
e- pair donor
O−H- (the O is e- rich)::. .. .. .. .
Lewis acids and basesLewis acids and bases
Lewis acid/base reactions:
H+(aq) + H2O(l) → H3O+(aq)
H3O+ is called a Lewis acid/base adduct.
NH3(g) + H+(aq) → NH4+(aq)
Cl3B(g) + :NH3(g) → Cl3B−NH3(s)
Cl3B−NH3 is called a Lewis acid/base adduct.
Lewis acid/base reactions:
H+(aq) + H2O(l) → H3O+(aq)
H3O+ is called a Lewis acid/base adduct.
NH3(g) + H+(aq) → NH4+(aq)
Cl3B(g) + :NH3(g) → Cl3B−NH3(s)
Cl3B−NH3 is called a Lewis acid/base adduct.
acids/bases theoriesacids/bases theories
Type Acid Base
Arrhenius H+ producer OH- producer
Brønsted-Lowry H+ donor H+ acceptor
Lewis e- pair acceptor e- pair donor