Variation of Conductance
with
Temperature in Electrolyte
Name: P.Mohana krishnan
Standard: XII
Index
1. Certificate.................................................................3
2. Acknowledgements.....................................................4
3. Aim..........................................................................5
4. Apparatus..................................................................6
5. Important Terms........................................................7
6. Conductivity...............................................................8
7. Factors Affecting Electrical Conductivity.........................9
8. Procedure.................................................................10
9. Physical Constants.....................................................11
10. Observation Set 1.....................................................12
11. Graph of Observation Set 1........................................13
12. Observation Set 2.....................................................14
13. Graph of Observation Set 2........................................15
14. Result.....................................................................16
15. Conclusion...............................................................17
16. Precautions..............................................................18
Aim:
To find the variation of conductance with temperature in
electrolytes.
Apparatus:
Glass beaker
CuSO4 solution
Cu electrodes
ZnSO4 solution
Zn electrodes
rheostat
battery eliminator
water
burner
Thermometer
flask
ammeter
voltmeter
Important Terms
Conductance: The property of ease of flow of electric current
through a body is called conductance.
Resistance: The obstacle offered to the flow of electric current is
called resistance.
Electrolysis: The operation in which electricity causes a chemical
reaction is called electrolysis.
Ohm's Law: This law states that the current flowing through a
resistance is directly proportional to the potential difference applied
across it's ends, at constant temperature and pressure. V = I x R
Faraday's Laws:
First Law: The mass of a substance produced or consumed in
electrolysis is directly proportional to the quantity of charge
passing through it. mQ
(or)
m=Z×I×t
where, Z is electrochemical equivalent; I is current; t is time in
seconds; Q is charge.
Second Law: The mass of substance produced in electrolysis
directly proportional to its equivalent mass.
W1 / E1 = W2 / E2 = W3 / E3...
Third Law: The mass of a substance produced in electrolysis is
directly proportional to the number of electrons per mole needed
to cause desired change in oxidation state
Conductivity
When voltage is applied to the electrodes immersed into an electrolyte
solution, ions of electrolyte move, and thus, electric current flows
through the electrolytic solution. The electrolytic solution and the
metal conductors exhibit resistance to the passage of the current; both
of which obey Ohm's law.
The reciprocal of resistance is called electrical conductance. The unit
of electrical conductance is Siemens (S) or ohm-1 or mho.
If a solution is placed between two parallel electrodes having cross
sectional area A and distance L apart then the resistance is given by
R=1/Cρ
(called 'rho') is known as resistivity. Its reciprocal gives the
conductivity of the solution, which is denoted by κ (called 'kappa'). Its
unit is Siemens/meter.
Κ=1/R*L/A
L / A is a fixed quantity for a cell and is called the 'cell constant’
Factors Affecting Electrical Conductivity
The factors which affect the electrical conductivity of the solutions
are:
Inter-ionic attraction: It depends on solute- solute interactions
Solvation of ions: It depends on solute-solvent interaction.
Viscosity of the solvent: It depends on solvent-solvent
interactions.
Procedure
1. The electrolyte chosen is ZnSO4 and the electrodes are of Zn.
2. Readings for the measurement of conductance are taken at
intervals of 3 C.
3. Proper precautions are taken to avoid evaporation and to keep
other factors constant.
4. The vessel and electrodes are removed and the vessel is cleaned
and filled with ZnSO4 solution.
5. The electrodes are refitted in their original place so that the
distance between them does not change
6. Current is passed and when the voltmeter and ammeter show
steady readings, they are noted.
7. The current is switched off.
8. It is seen that while the ammeter reading returns at once to 0
position. The voltmeter needle pauses for a while at a particular
reading which is noted down.
9. This reading indicates the back EMF in the electrolyte.
10. Similarly, more sets of reading are taken, and resistance is
calculated.
11. Thus, the value of conductance is calculated.
12. The switched-on circuit readings in voltmeter and ammeter
are taken.
13. The current through the electrolyte is changed by adjusting
the rheostat and more sets of readings are taken
14. Thus, the mean value of resistance is calculated.
15. Above steps are repeated for CuSO4 as electrolyte with
electrodes made of Cu
Physical Constants
For the purpose of accuracy and convenience, some important
aspects of the electrolyte process are kept constant in the experiment
as their variation might affect the conductivity of the electrolyte. They
are:
Voltage
Nature of electrodes
Size of electrodes
Separation between the electrodes
Concentration of the electrolytes
Nature of the electrolytes
Resistance in the circuit
Observation Set 1
For ZnSO4 electrolyte with Zn electrodes
Graph of Observation Set 1
Observation Set 2
For CuSO4 electrolyte
Graph of Observation Set 2
Copper Sulphate Electrolyte
Temperature (in degree Celsius)
Result
The relevant graph shows that the 1 / Resistance of an electrolyte
increases at a steady rate as the temperature increases
Conclusion
On heating a solution, it is known that viscosity gradually decreases,
with decrease in viscosity, the speed and movement of the ions
increases. In other words, the conductance of the electrolyte increases
with increases in temperature. Hence, the result of the experiment
agrees with reasoning
