Measurement of conductance and kohlrausch's law.pdf

This ppt is about measurement of conductance along with Kohlrausch's law. This topic is included in physical chemistry.
This ppt is at the level of msc chemistry 6th semester.
This is special for student's guidance to make their presentations during their studies.
This ppt provides a detail and easy information about measurement of conductance. This also provide enough information about Kohlrausch's law.
This can be helpful for physics students.

1. Physical chemistry
CHEM-303
01
TOPIC
Measurement of conductance and
Kohlrausch’s Law
UOG (Chemistry Department)

2. Presented To:
Dr.Sumaira Naeem
Presented by: Masooma Liaqat Ali
Roll No. 21017107-004
02

3. Table of Contents Slide No.
Measurement of conductance
Cell constant
Determination of the cell constant
Kohlrauschs law
Applications of Kohlrauschs law
Calculation of λ∞for weak electrolytes
Calculation for absolute ionic
mobilities
Calculation of the solubility of the
sparingly soluble salts
Calculation of the degree of
dissociation or conductance ratio
Calculation of the ionic product for
water
Uses of Kohlrauschs law
References
05-06
06-08
09-10
11-12
13-14
15
16
17-18
19-20
21
22
23
03

4. Table of Figures Slide no
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
06
07
09
18
19
04

5. Measurement of conductance
Conductance is reciprocal of resistance.
This can be done in laboratory by Wheatstone Bridge.
The solution whose conductance is to be measured it placed in
special type of cell that is called Conductance Cell.
The electrodes are made up of platinum.
Head phone is used in this cell instead of galvanometer
05

6. Continued…..
06
Fig.; 1.1 A Conductance Cell

7. Continued………
07
Fig.; 1.2 Apparatus for conductance measurement

8. Continued………
08

9. Determination of the cell constant: 09
Fig.; 1.3 Dimensions of a conductance cell

10. Continued……
According to Kohlrauschs the specific conductance of
N/50 solution at 25c 0.002765 mho.
Now an N/50 solution of KCl is prepared by dissolving
0.372g pure KCl in 250cc extra pure water and its
conductance determined at 250c.
The is constant is then calculated by substituting the
observed conductance in the expression.
10

11. Kohlrausch’s Law
Applications of Kohlrausch’s law
11

12. What is Kohlrauschs law?
The equivalent conductance of an electrolyte at infinite dilution id
equal to the sum of the equivalent conductance of the component
ions.
12

13. Applications of Kohlrausch’s Law
13

14. Continued…….
1.Calculation of λ∞for weak electrolytes.
2.Calculation of Absolute ionic motilities.
3.Calculation of the solubility of sparingly soluble salts.
4.Calculation of the degree of Dissociation or Conductance Ratio.
5.Calculation of the ionic product for water.
14

15. 1 Calculation for λ∞for weak electrolytes:
15
Fig.; 1.4 Value for λ∞in electrolytes

16. 2 Calculation of absolute ionic mobilities:
16
Fig.; 1.5 Ionic mobilities(cations and anions)

17. 3 Calculation of the solubility of the sparingly soluble
salts:
17
Fig.; 1.6 Solubilities of sparingly soluble salts

18. Continued…..
18
Fig.; 1.7 Sparingly soluble salts with salt bridge

19. 4 Calculation of the degree of dissociation or conductance ratio:
19
Fig.; 1.8 Dissociation of charges or ions

20. Continued……..
20
Fig.; 1.9 Dissociation values of salts

21. 5 Calculation of the ionic product for water:
21
Fig.; 2.1 Ionic product for water ions

22. Uses of Kohlrausch’s Law…….
22

23. References:
Essential off physical chemistry by Bhall.
Levine I.R physical chemistry McGraw Hill 5
th
edition.
Conductance and conductance mechanism and
effects of molecule electrode constant by F Am
chem 9
th
edition.
Physical chemistry by haq Nawaz Bhatti.
23