This document discusses the application of conductance measurements in chemistry. It describes five uses: 1) determining the degree of dissociation of weak electrolytes, 2) determining ionization constants of acids, 3) determining solubility products of sparingly soluble salts, 4) calculating the ionic product of water, and 5) conductometric titration. Conductometric titration involves measuring conductivity during a titration to determine the endpoint, which occurs when conductivity remains constant as the neutralization point is reached. Factors that affect conductivity include the size, temperature, charge, and number of ions in solution.

1. Presented by : Sara Anwar
Topic : “APPLICATION OF CONDUCTANCE
MEASUREMENT”

2. 1: Determination of degree of dissociation of weak electrolyte
2: Determination of ionization constant of acids
3: Determination of solubilty product (ksp ) of sparingly soluble salt
4: Calculation of ionic product of water
5: Conductometric titration

3. Determination of degree of dissociation:
• “Degree of dissociation is the fraction of the total number of molecules
dissociated into ions.”
Degree of dissociation (ᾳ) = No. of molecules dissociated into ions
Total no. of molecules present
• No. of molecules dissociated is directly proportional to
conductivity of the molecules.
• No. of molecules dissociated in to ions λm
c ( molar conductivity
at a particular concentration.)
• Total no. of molecules λm
∞(molar conductivity at infinite
concentration)
ᾳ(degree of dissociation) = λm
c / λm
∞
1:

4. 2:Determination of ionization constant of acids:
• The acid ionization constant, also called the 'acid dissociation
constant' or 'acidity constant,' is a measure of how much of the acid
is deprotonated (which is when it's unbound to a hydrogen),
compared to molecules still bound to a hydrogen.
• example :acetic acid
(left) (right)
CH3 COOH CH3 COO_ + H+
at time 0 C 0 0
t C-Cᾳ Cᾳ Cᾳ
[Cᾳ is dissociated part ]

5. According to the law of mass action :
“The rate of chemical reaction is directly
proportional to the product of active masses of
reactiong substances.”
Ka = Cᾳ Cᾳ
C(1-ᾳ)
Ka =CᾳCᾳ
C(1-ᾳ)
Ka =Cᾳ2
1-ᾳ [ᾳ is of
dissociation ]

6. 3)Determination of solubility product (ksp) of
sparingly soluble salt :
Solubility product:
• When a sparingly soluble salt is placed in water, a very small amount
of the salt dissolves in the water and a solution is formed. The
solubility product, Ksp, determines the equilibrium that exists
between the sparingly soluble salt and the ions that are dissolved in
water
Example :
AgCl (s) Ag+
(aq) + Cl-
(aq)

7. Ksp = [Ag+ ][Cl- ]
if the s is the solubilty of AgCl then :
[Ag+ ] =s & [Cl- ]=s
Ksp =(s) (s)
Ksp =s2

8. 4)Calculation of ionic product of water:
• Water has electrical conductivity, hence it must undergo dissociation .
Dissociation of pure water to a very little extent into H+ and OH – ions by
itself is called as self ionization of water .
• Water is very weak electrolyte . In water an equilibrium between ions an
unionized water molecules exists as :
H2O H+ + OH-
H+ + H2O H3O+
the net reaction is
H2O + H2O H3O+ +OH-

9. • Applying the law of mass action to above equilibirium , we have
kW =[H3O+][OH-]/ [H2O]2 (1)
Now water is very weak electrolyte . It dissociate in a very small
amount . Hence practically the concentration of unionized water is
almost the same as starting concentration .hence H2O =1=constant .
• similarly that H+
(aq) actually refers to a hydroxonium ion. Therefore the
1st equation becomes:
kW [constant]=[H+][OH-] (2)
KW =[H+ ][OH- ]
the relation is known as the ionic product of water

10. • When small amount of acid is added to water , the concentration of
[H+ ] increases and the concentration of [OH- ] decreases
• When small amount of alkali is added to water , [OH- ] ions
concentration becomes higher than that of [H+ ] ion concentration
• In neutral solution, [H+ ] and [OH- ] ion concentration are equal
• Thus the concept of ionic products of water helps us in classifying the
aqueous solution as an acid , base or neutral.

11. 5) CONDUCTOMETRIC TITRATION
• “The determination of end point of a titration by the means of
conductivity measurements are known as conductometric titration”
TYPES OF CONDUCTOMETRIC TITRATIONS
• acid-base titration
• Precipitation titration
• Replacement titration
• Redox ( oxidation-reduction) titration
• Complexometric titration

12. -
-
-
-
Burette (strong acid
e.g HCL)
Electrodes
Battery +
__
Beaker (strong
base e.g NAOH)
CONDUCTOMETER
Acid – base titration :
HCL
NAOHH2O+NACL

13. HCL
NAOH
1
2
3

14. FACTORS AFFECTING CONDUCTIVITY:
• Size of ions
• Temperature
• Charge of ions
• Numbers of ions

15. Principals:
• Conductometry is the ability to measure the ability of electrolyte
carry current .
• Conductrometry is depends on the ions present in the electrolyte .
• As the number of ions in the solution decreases the conductivity
decreases and vise versa .
• The point from which the conductance remains constant is
neutralization point which indicates the end point of reaction .

16. Advantages of the conduct metric titration :
• No need of indicator
• Colored or dilute solution can be used for titration .
• End point can be determined accurately.

17. THANK YOU