The document discusses acids and bases according to different theories including Arrhenius, Bronsted-Lowry, and Lewis concepts. It defines acids and bases, describes their properties, and explains neutralization reactions. Examples are provided of strong vs weak acids and bases as well as monoprotic, diprotic, and triprotic acids and bases based on their equivalent weights.

2. Acids and Bases are two classes of chemical
compounds that display generally opposite
characteristics.
When aqueous solution of an acid and a base are
combines, a neutralization reaction occurs.
This reaction is very rapid and generally produces
water and a salt.
HCl + NaOH NaCl + H2O

3. Acids:----
a)Turns blue litmus red,
b)Has sour taste,
c)Conducts electricity,
d)Reacted with certain metals to give off
hydrogen gas,
e)Reacted with carbonates to evolve carbon
dioxide gas, and
f)Reacted with bases to neutralize them.

4. Bases:----
a)Turns red litmus blue,
b)Has bitter taste,
c)Conducts electricity,
d)Has a soapy, slippery touch, and
e)Reacted with acids to neutralize them.

5. Arrhenius Concept of Acids & Bases
a) An acid is a substance which gives
hydrogen ions, H+ when dissolved in
water.
b) A base is a substance which gives
hydroxyl ions, OH- when dissolved in
water.
c) Neutralization is the combination of H+
ions from acid and OH- ions from the base
forming H2O.

6. Acids
HCl H+ + Cl-
H2SO4 H+ + SO42-
HNO3 H+ + NO3-
CH3COOH H+ + CH3COO-
Bases
NaOH Na+ + OH-
KOH K+ + OH-
Neutralization
H+ + OH- H2O

7. Lewis Concept of Acids & Bases
a) An acid is an electron pair acceptor.
b) A base is an electron pair donor.
c) During neutralization, base donates an
electron pair to the acid forming a
co-ordinate bond.

8. Lewis Acids:-----
BF3, AlCl3, SnCl4, H+
Lewis Bases:-----
NH3, H2O, OH-
Neutralization:-----
H F H F
H N: + B F H N B F
H F H F

10. Strong acids: An acid which is completely ionized
in water and thus produces a large number of
hydrogen ions is called a strong acid.
“Strong” means “Degree of ionization”
HCl aq H+ aq + Cl- aq
H2SO4 aq H+ aq + SO42- aq
HNO3 aq H+ aq + NO3- aq

11. Weak acids: An acid which is partially ionized in
water and thus produces a small number of
hydrogen ions is called a weak acid.
HCN aq H+ aq + CN- aq
H3PO4 aq H+ aq + PO42- aq
CH3COOH aq H+ aq + CH3COO- aq

13. Strong bases: A base which is completely ionized
in water and thus produces a large number of
hydroxide ions is called a strong base.
NaOHaq Na+ aq + OH-aq
KOH aq K+ aq + OH-aq

14. Weak bases: A base which is only partially ionized
in water and thus produces a small number of
hydroxide ions is called a weak base.
NH4OHaq NH4+ aq + OH-aq
Mg(OH)2 aq Mg2+ aq + OH-aq
Ca(OH)2 aq Ca2+ aq + OH-aq

16. Basicity of an acid is the number of replaceable or
ionisable hydrogen atoms present in a molecule of
the acid.
HCl, HNO3, CH3COOH ……..Basicity = 1
Simply……..Monobasic acids
H2SO4, H2CO3 ………Basicity = 2
Simply……..Dibasic acids
H3PO4 ………..Basicity = 3
Simply……..Tribasic acids

17. Acidity of the base is the number of replaceable
or ionisable hydroxyl groups present in a molecule
of the base.
NaOH, KOH ……..Acidity = 1
Simply……..Monoacidic bases
Ca(OH)2, Mg(OH)2, ………Acidity = 2
Simply……..Diacidic bases
Fe(OH)3, Al(OH)3………..Acidity = 3
Simply……..Triacidic bases

19. Consider two reactions……………….
HCl + NaOH NaCl + H2O
H2SO4 + 2NaOH Na2SO4 + 2H2O
Examine the number of H+ needed to react
with one molecule of base.
Get your
answer…!

20. Consider two more reactions…………
2HCl + Ca(OH)2 CaCl2 + 2H2O
2HCl + Na2CO3 2NaCl+ CO2 + H2O
Examine the number of OH- or +ve ion
needed to react with one molecule of acid.
Get your
answer…!

21. Molecular weight
Equivalent weight of an acid =
Basicity
Molecular weight
Equivalent weight of a base =
Acidity

22. Acid/ Chemical Molecular Acidity or Eq. weight
Base Formula weight Basicity
Acid HCl 36.5 1 36.5
Acid HNO3 63 1 63
Acid H2SO4 98 2 49
Acid CH3COOH 60 1 60
Acid H2C2O4.2H2O 126 2 63
Base NaOH 40 1 40
Base KOH 56.1 1 56.1
Base Ca(OH)2 74 2 37
Base Mg(OH)2 58 2 29
Base Fe(OH)3 107 3 35.66
Base Al(OH)3 78 3 26

23. The weight of the acid
which contains one
part by weight of
replaceable hydrogen
atom.
Equivalent = Equal, Corresponding, Comparable, the same.

24. The weight of the
base
which neutralizes
one equivalent of
an acid.

25. How Much You Have Followed ?

26. Electronic Concept

27. According to electronic Concept…….
Oxidation means Loss of electrons
M M+ + e-
Reduction means Gain of electrons
M + e- M-

28. During Redox reaction,
Oxidation and reduction will take place
together.
An oxidising agent will get reduced and
reducing agent will get oxidised.
Understand…….
oxidising agent……
reducing agent……

29. Oxidation Number
Oxidation number or oxidation state is
defined by the total number of electrons
that an atom either gains or loses in order
to form a chemical bond with another
atom.
Make it by heart……..!

30. Rules for assigning oxidation number
1 The algebraic sum of the oxidation numbers of all atoms in a compound is
zero.
2 Oxidation number of an element in its elementary state is zero.
3 Oxidation number of all metals in all compounds is positive.
4 Oxidation number of all non-metals in all compounds is negative.
5 Oxidation number of hydrogen is +1, but in hydrides it is -1. (NaH, MgH 2)
6 Oxidation number of oxygen is -2, but in peroxides it is -1 and in OF 2 it is
+2.
7 Oxidation number of first group element is is +1 and that of second group
element it is +2.
8 The oxidation number of the elements in their molecules like H 2, N2, Cl2,
Br2, O2 etc is zero.
9 The oxidation number of a simple ion is equal to the charge on the ion.

31. Find the oxidation numbers of S in i) H2SO4 ii) Na2SO4 iii) H2S
O N of H = +1, O = -2…….So O N of S = X
In H2SO4, 1x2 + X + -2x4 = 2+X-8 = 0
X-6 = 0, ie, X = 6
O N of Na = +1, O = -2…….So O N of S = X
In Na2SO4, 1x2 + X + -2x4 = 2+X-8 = 0
X-6 = 0, ie, X = 6
O N of H = +1, …….So O N of S = X
In H2S, 1x2 + X = 2+X = 0 ie, X = -2

32. Do the problems from text book….

34. Observe the reactions at the electrodes
- +
battery
Cl2 (g) escapes
Na (l)
NaCl (l)
Na+
Cl- Na+
Cl-
(-) (+)
electrode electrode
half-cell Cl- Na+ half-cell
Na+ + e-  Na 2Cl-  Cl2 + 2e-

35. Commercial form of Daniel Cell

36. Salt bridge –
Cell
KCl in agar
Construction Provides conduction
between half-cells
Observe the
electrodes to
see what is
occurring.
Cu Zn
1.0 M CuSO4 1.0 M ZnSO4

37. What about half-cell What about the sign of
reactions? the electrodes?
+ -
Why?
cathode half-cell anode half-cell
Cu+2 + 2e-  Cu Zn  Zn+2 + 2e-
Cu Zn electrode
deposits on What erodes
electrode happened at or dissolves
Cu each Zn
electrode?
1.0 M CuSO4 1.0 M ZnSO4

38. Definitions:
CATHODE
REDUCTION occurs at this electrode
ANODE
OXIDATION occurs at this electrode

39. Zn  Zn+2 + 2e- Anode
Cu+2 + 2e-  Cu Cathode
Zinc plate is eaten away and Copper deposits on the
copper plate. Electrons produced at the zinc anode flow
through the outer circuit to the copper cathode.
Electric Current is assumed to flow from copper to zinc,
ie, from positive terminal to negative terminal.

40. Electricity can be produced by connecting two
different metals in solutions of their metal ions.
e- e-
Copper
A Zinc
Ion/salt bridge
Copper sulphate solution Zinc sulphate solution

41. The purpose of the “ion bridge” (“salt bridge”) is to
complete the circuit.
e- e-
Copper
A Zinc
Ion/salt bridge
Copper sulphate solution Zinc sulphate solution

42. Parts of Daniel cell
1.Two half cells, namely zinc half cell and copper half cell.
In the former is a zinc rod dipped in a ZnSO4 solution and the
latter is a copper rod dipped in a CuSO4 solution. The two
metallic rods are called electrodes.
2. The two half cells are connected externally by a metallic wire
to a galvanometer through a key and internally by a salt bridge.
3. The salt bridge is an inverted U-tube containing an arouse
solution of an inert salt like KCl, KNO3, NH4NO3 to which some
agar-agar or gelatin has been added to convert it into a semi solid,
ie gel. The ends of the U-tube are plugged with glass wool.

43. 1.Permits the passage of electric current internally,
2.Maintains the electrical neutrality of the solution,
3.Prevents intermixing of the solutions,
4.It does not take part in cell reaction.
Representation of Daniel Cell
Zn(s) / Zn2+(aq) // Cu2+(aq)/Cu(s)