EQUILIBRIUM
PART- II
y ACIDS
¾Defination
D fi ti
¾Basicity of an acid
¾Classification
Cl
ifi ti off acids
id
y BASES
¾Defination
¾Acidity of base
¾Classification of bases
y ALKALI
y NEUTRALISATION
y SALTS
ACIDS USED IN DAILY LIFE.
LIFE
y Milk contains lactic acid.
y Carbonic acid is responsible for the
fizz in soft drinks.
ƒAscorbic
A
bi acid
id is
i the
th chemical
h i l name off
vitamin –C.
ƒVinegar used in cooking contains
approximately 4 % acetic acid.
ƒSulphuric acid is used in the manufacture
of car batteries.
T il t cleaner
Toilet
l
What is an acid?
ACIDS
An acid is a substance which contains one
or more replaceable hydrogen atoms and
dissociates in solution giving hydrogen
ions( H+ ).
)
Ex : 2 HCl + 2 Na→ 2NaCl + H2
one molecule of HCl contains one
replaceable hydrogen
h drogen atom
atom.
HCl (aq) → H+ + Cl-
y H2SO4 (aq) + Zn
Z → ZnSO
Z SO4 + H2
o e molecule
one
o ecu e o
of H2SO4 co
contains
ta s ttwo
o
replaceable hydrogen atoms.
y H2SO4 (aq) → 2 H+ + SO4 2y HNO3 (aq) →
H+ + NO3 –
y CH3COOH +NaHCO3 →
CH3COONa
COON + CO2 + H2O
one molecule of CH3COOH contains one
replaceable hydrogen atom.
y CH3COOH (aq) → H+ + CH3COO –
g
Mineral acids and organic
acids.
y A mineral acid (or inorganic acid) is
an acid derived from one or
more inorganic
g
compounds.
p
y All mineral acids form hydrogen ions
when dissolved in water.
Ex: HCl , HNO3 H2SO4 etc
Organic compounds having acidic
property
p
p y are organic
g
acids.
Ex: Carboxylic acids
HCOOH
CH3COOH
C6H5COOH
BASICITY OF AN ACID
It is the number of replaceable hydrogen
atoms present in a molecule of an acid.
CLASSIFICATION OF ACIDS :
Depending
D
di on th
the b
basicity
i it off th
the acids,
id
theyy are classified as:
y Monobasic acid
y Dibasic
Dib i acid
id
y Tribasic acid etc.
MONOBASIC ACID
Monobasic acid contains one replaceable
hydrogen atom in a molecule.
Ex :
Hydrochloric
y
acid - HCl
Nitric acid
- HNO3
For organic acids basicity is the number of
-COOH groups present in the molecule
molecule.
Ex :
HCOOH
CH3COOH
C6H5COOH
DIBASIC ACID
Dibasic acid contains two replaceable
hydrogen atoms in a molecule.
Ex :
Sulphuric acid - H2SO4
Oxalic acid
- C2 H2O4
( HOOC – COOH))
TRIBASIC ACID
A tribasic acid contains three replaceable
hydrogen atoms in a molecule.
Ex :
Orthophosphoric acid - H3PO4
y Almost all inorganic acids are soluble in
water
water.
y For volumetric analysis, solution of acids
having different concentrations are
p p
prepared.
y Concentration of acids are expressed in
normality or molarity.
Why SO3 , BF3 etc are acids?
BASES USED IN DAILY LIFE.
Antacids help to neutralize the acidity in
the
th stomach.
t
h
They mainly contain two bases:
„ Mg(OH)2
&
„ Al(OH)3
Potassium hydroxide is used in the
manufacture of alkaline batteries
batteries.
Ammonia is a basic gas which is
used in the manufacture of
fertilizers such as :
y urea
y ammonium nitrate
y ammonium phosphate.
What is a base?
BASES
y A base is a substance which dissociates
in solution giving hydroxyl ( OH - ) ions.
ions
Th oxides
The
id and
dh
hydroxides
d id off metals
t l
are bases or basic in nature.
Ex : Sodium hydroxide ( NaOH )is a
base.
NaOH dissociates in solution
NaOH → Na+ + OH –
y
Calcium hydroxide Ca(OH)2 is a base
Ca(OH)2 dissociates in solution
solution.
Ca(OH)2 → Ca2+ + 2 OH –
y Aluminium hydroxide Al(OH)3 is a base
Al(OH)3 dissociates in solution.
Al(OH)3 → Al3+ + 3 OH –
y
ACIDITY OF BASE
It is the number of molecules of
monobasic acid required to neutralize
one molecule of a base.
Ex : NaOH + HCl → NaCl + H2O
Acidity of NaOH is one
or
NaOH is monoacidic base.
Ca(OH)2 + 2HCl → CaCl2 + 2H2O
Acidity of Ca(OH)2 is two
or
Ca(OH)2 is diacidic base.
Al(OH)3 + 3HCl → AlCl3 + 3H2O
Acidity of Al(OH)3 is three
or
Al(OH)3 is triacidic base
base.
ACIDITY OF BASE
Acidityy of hydroxide
y
is the number
of hydroxyl (OH) groups present in a
molecule of itit.
Base
NaOH
Ca(OH)2
Al(OH)3
Acidity
1
2
3
H
How
tto d
detect
t t the
th acids
id & b
bases?
?
y Acids turns blue litmus to red.
red
y Bases turns red litmus to blue.
Why CaO ,MgO are bases?
ALKALI
The bases which are readily
soluble in water are called alkali
alkali.
yOxides and hydroxides of “group - 1 ’’
metals of long form of periodic table are
readily soluble in water. They are called
alkalies.
alkalies
yThese metals are called alkali metals.
Ex:
y NaOH is a base and also an alkali.
y KOH is a base and also an alkali.
y Mg(OH)2, Ca(OH)2 are bases only but not
alkalies.
All the alkalies are bases but all the bases
are not alkalies.
NEUTRALISATION
The reaction between an
acid and a base in dilute
aqueous solution is called
neutralisation reaction.
Ex: HCl(aq)+ NaOH (aq)→ NaCl(aq) + H2O
H2SO4(aq)+ 2NaOH
2N OH (aq)→Na
N 2SO4 (aq) + 2H2O
CH3COOH +NaOH → CH3COONa + H2O
What are salts?
SALT
The Chemical substance obtained as a
result of neutralisation reaction between
an acid and a base is called salt.
Ex: HCl(aq)+ NaOH(aq) →NaCl(aq)+ H2O
y H2SO4 (aq)+ 2NaOH(aq)→Na2SO4(aq)+2H2O
y HNO3 ((aq)
q) + NaOH((aq)
q) → NaNO3(aq)
( q) +H2O
y HCl(aq)
+ KOH(aq)
y HNO3 (aq) + KOH(aq)
→ KCl(aq)
+H2O
→ KNO3(aq) +H2O