Acid- Base
Chemistry
Properties of Acid and Base
Properties
Acid
Base
Tase
Tard/ Sour
Bitter
Texture
Rough
Soapy and slippery
pH
Less than 7
Greater than 7
Turns litmus paper..
Blue  Red
Red  Blue
Reactivity
– Reacts with metals to produce
H2 gas
– Reacts with carbonated
compounds to produce CO2
– Does not typically react with
metals or with carbonated
compounds
– Does react with oils and fats
Conducts electricity in water
yes
yes
Examples
vinegar (ethanoic acid) , lemon
juice (citric acid)
Baking soda (sodium
bicarbonate), ammonia water
(ammonia hydroxide)
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Arrhenius Theories of acid and base
Arrhenius acids are substances which produce
hydrogen ions in solution.
HCl(aq)  H+(aq) + Cl-(aq)
Arrhenius bases are substances which produce
hydroxide ions in solution.
NaOH(aq)  Na+(aq) + OH-(aq)
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A Brønsted-Lowry Theories of acid and base
A Brønsted-Lowry acid is a proton (hydrogen
ion) donor.
A Brønsted-Lowry base is a proton (hydrogen
ion) acceptor.
HCl (aq)+NH3 (aq)→NH4+ (aq)+Cl- (aq)
A compound that acts as both a Brønsted-Lowry acid and base together is called
amphoteric. It can lose or gain a proton, depending on the other reactant. For example,
HCO3- acts as an acid in the presence of OH- but as a base in the presence of HF.
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A strong acid
A strong acid is a substance that completely ionizes in aqueous
solution to give H3O+(aq) and an anion.
HClO4(aq) + H2O(l )  H3O+(aq) + ClO4-(aq)
Eg. H2SO4, HCl, HI, HBr, HNO3
A strong base
A strong base completely ionizes in aqueous solution to give OHand a cation.
NaOH(aq)  Na+(aq) + OH-(aq)
Eg. hydroxides of Group IA 5 elements and Group IIA elements
(except Be).
Acid and base are weak which can not completely
ionized in solution and exist in reversible reaction with
the corresponding ions.
CH3COOH (aq)
CH3COO- (aq) + H+ (aq)
A conjugate acid–base pair consists of two species in an acid–base reaction,
one acid and one base, that differ by the loss or gain of a proton. The acid in
such a pair is called the conjugate acid of the base, whereas the base is the
conjugate base of the acid.
A Lewis concept of acid and base
Lewis acid is a species that can form a
covalent bond by accepting an electron
pair from another species.
Lewis base is a species that can form a
covalent bond by donating an electron pair
to another species.
Life Science
Taking your medicine
many medicinal substances are nitrogen bases, substances that organic chemists call
amines.
Quinine (antimalarial)
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Stronger acids are those lose their protons more easily than other acids.
Similarly, the stronger bases are those that hold on to protons more strongly
than other bases.
The strongest acids have the weakest conjugate bases and the strongest
bases have the weakest conjugate acids.
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Molecular Structure
How easily the proton is lost or remove and H-X bond
1. Polarity of the bond.
The more polarized the bond, the more easily the proton is removed and the greater
the acid strength.
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2. Strength of the bond
The larger the atom X, the weaker the bond and the greater the acid strength.
For a series of oxoacids of the same structure, differing only in the atom Y, the acid
strength increases with the electronegativity of Y.
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For a series of oxoacids, (HO)mYOn, the acid strength increases with n, the number
of O atoms bonded to Y (excluding O atoms in OH groups).
The acid strength of a polyprotic acid and its anions decreases with increasing negative
charge
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Self ionization of water and pH
Aqueous solution  Hydronium ion (H3O+) or Hydrogen ion (H+) and Hydroxide ion
(OH-)
Pure water (H2O)  non electrolyte  but very small conduction  self ionization or
auto ionization
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