Chem Project 12

CHEMISTRY

INVESTIGATORY

PROJECT TOPIC: Variance in conductivity of solution PROJECT BY: Chinmay Shah

CLASS: XII-B

GUIDED BY: Mrs Priyanka Sinha

BOARD ROLL NO:

Chemistry Investigatory Project Chinmay Shah

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CERTIFICATE This is to certify that Chinmay Shah , student of class XII-B has successfully completed the Chemistry Project under the guidance of Mrs Priyanka Sinha. This project is genuine and is not plagiarism of any kind. The references used in making this project file are declared at the end of the file.

External’s Sign: Internal’s Sign

______________ _____________

Principal’s signature School stamp


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ACKNOWLEDGEMENT

I wish to express my deep gratitude and sincere thanks to the Principal, Mrs Murial Fernandez, Ryan International School, Sanpada for her encouragement and for all the facilities she has provided for this project work. I extend my hearty thanks to my subject teacher Mrs Priyanka Sinha and Lab Assistant Devesh Sir who guided me to the successful completion of this project. I take this opportunity to express my deep sense of gratitude for their invaluable guidance, constant encouragement and immense motivation which has sustained my efforts at all stages of this project work. I

can’t forget to offer my sincere thanks to my

classmates who helped me to carry out this project work successfully and for their valuable advice and support which I received for them time to time.


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INDEX

Sr No. Contents Page No.

1 Aim of the Experiment 5

2 Introduction 6

3 Apparatus Required 7

4 Theory 8

5 Procedure 10

6 Physical Constants 13

7 Observation and Graph 14

8 Result 20

9 Conclusion 21

10 Precautions 22

11 Bibliography 23


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AIM

To find the variation of conductance with temperature and concentration in electrolytes


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INTRODUCTION

• Conductivity is the ability of a solution to pass an

electric current.

• This depends on a number of factors including

concentration, mobility of the ions, valence of the

ions and temperature. As the temperature of a

solution increases, the mobility of the ions in the

solution also increases and consequently this will

lead to an increase in its conductivity.

• Pure water does not conduct electricity, but any

solvated ionic species would contribute to conduction

of electricity. An ionically conducting solution is

called an electrolyte solution and the compound,

which produces the ions as it dissolves, is called an

electrolyte.

• The conductivity of an electrolyte solution depends

on concentration of the ionic species and behaves

differently for strong and weak electrolytes. The

conductivity also changes with change in

temperature due to difference in viscosity of liquid.

• In this work the electric conductivity of water

containing various electrolytes will be studied with

varying temperature and concentration.


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APPARATUS REQUIRED

1) Glass beakers; 2) CuSO4 solution; 3) ZnSO4 solution; 4) Rheostat; 5) Bunsen Burner; 6) Ammeter; 7) Voltmeter; 8) Thermometer; 9) Measuring Flask; 10) Electrodes; 11) Tripod Stand; 12) Wire Gauze; 13) Weighing Scale; 14) Spatulas and Stirrers;


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THEORY

• Movement of ions in water can be studied by

installing a pair of electrodes into the liquid and by

introducing a potential difference between the

electrodes. Like metallic conducting materials,

electrolyte solutions follow Ohm’s law:

R = V/I

where R is the resistance (Ω,“ohms”), V is the

potential difference (V,“Volts”) ,and I is the current

(A,“Amperes”).

• Conductance G (S, Siemens or Ω−1

) is then defined

as reciprocal of the resistance:

G = 1/R

• Conductance of a given liquid sample decreases

when the distance between the electrodes increases

and increases when the effective area of the

electrodes increases. This is shown in the following

relation:

G = κ

where κ is the conductivity (S m−1

), A is the cross-

sectional area of the electrodes (m2 ; i.e., the effective

area available for conducting electrons through the

liquid), and l is the distance between the electrodes

(m).


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• Molar conductivity Λm (S m2 mol

−1 ) is defined as:

Λm = κ / c

where c is the molar concentration of the added

electrolyte.

• The factors which affect the electrical conductivity of

the solutions are:

1. The nature of the electrolyte added;

2. Size of the ions produced and dissolution;

3. The nature of the solvent and its viscosity;

4. Concentration of the electrolyte;

5. Temperature (it increases with the increase of

temperature);

The variation is different for strong and weak

electrolytes.

• For Strong Electrolytes, It is given according to the

equation:

are the molar conductance at a given

concentration and at infinite dilution (respectively). b is

a constant depending on the viscosity of the

solvent. decreases as the concentration increases.


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PROCEDURE

The electrolyte chosen is CuSO4

• 1.5g of CuSO4 is measured and put in a solution

containing constant volume of 150 mL:

• The vessel and electrodes are removed and the vessel is cleaned and filled with CuSO4 solution.

• The electrodes are refitted back into the vessel at their original place so that the distance between them does not change. A thermometer is also put in the electrolyte.

• Current is passed and when the Voltmeter and Ammeter show steady readings, they are noted at a constant temperature which is recorded by the thermometer.


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• Ammeter and Voltmeter readings taken

• When the current is switched off -

- It is seen that while the reading of the current returns at once to 0 position, the voltmeter needle pauses for a while at a particular reading which is noted down.

- This reading indicates the back EMF in the electrolyte.

• Similarly, more sets of reading are taken at same, as well as different values of temperature along with different values of concentration [with 1.5g, 3g, 7g].

• Temperature is changed my supplying heat through a Bunsen Burner.

• Value of Resistance is calculated using Ohm’s Law. Thus, the value of conductance is also calculated.

• The switched on circuit readings in voltmeter and ammeter are noted.


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• The current through the electrolyte is changed by adjusting the rheostat and more sets of readings are taken. Voltage is also changed.

• Thus, the mean value of resistance is calculated. Above steps are repeated for ZnSO4 as electrolyte and the readings are recorded at different values of temperature and at different concentration of the solution. The mass taken is 5g,7g and 9g and volume of the solution is 150 mL.


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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 ELECTRODES;

- VOLUME OF THE ELECTROLYTES [150 mL];


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OBSERVATION For CuSO4 electrolyte: Concentration (M)

Temperature (°C)

Ammeter reading[I] (mA)

Voltmeter reading [V] (V)

Resistance R=V / I (Ω)

Conductance G=1 / R (S)

0.0626 33 17.56 2.35 134.603 0.0074

35 17.62 2.35 133.333 0.0075

50 17.74 2.15 121.168 0.0083

0.125 33 33.032 2.1 69.369 0.0144

35 33.250 2.005 66.6665 0.0150

43 38.353 1.565 57.530 0.0173

50 23.748 2.13 50.584 0.0197

0.292 35 17.465 2.023 35.333 0.0283

40 7.9193 1.406 17.754 0.0458

50 9.2486 1.523 16.467 0.0607


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Temperature vs. Conductance (keeping Concentration Constant):

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

35.0 36.0 37.0 38.0 39.0 40.0 41.0 42.0 43.0 44.0 45.0 46.0 47.0 48.0 49.0 50.0

Conducta

nce

Temperature

0.0626 M

0.125 M

0.292 M


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Concentration Vs. Conductance (Keeping Temperature constant at 35°C):

0

0.0075

0.015

0.0225

0.03

0.0626 0.125 0.292

Co

nd

ucta

nce

(S

)

Concenteration (M)

T= 35°C


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For ZnSO4 electrolyte: Concentration (M)

Temperature (°C)

Ammeter reading[I] (mA)

Voltmeter reading [V] (V)

Resistance R=V / I (Ω)

Conductance G=1 / R (S)

0.206 35 50.9925 3.21 6.295 0.1588

40 50.629 3.16 6.241 0.1602

50 46.098 2.85 6.182 0.1617

0.289 35 44.194 2.72 6.154 0.1624

40 42.711 2.6 6.146 0.1626

50 42.657 2.6 6.118 0.1634

0.366 35 43.366 2.66 6.133 0.1630

40 41.958 2.57 6.125 0.1632

50 42.865 2.62 6.112 0.1636


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Temperature vs. Conductance (keeping Concentration Constant):

0.156

0.157

0.158

0.159

0.16

0.161

0.162

0.163

0.164

35.0 36.0 37.0 38.0 39.0 40.0 41.0 42.0 43.0 44.0 45.0 46.0 47.0 48.0 49.0 50.0

Conducta

nce

Temperature

0.206 M

0.289 M

0.366 M


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Concentration Vs. Conductance (Keeping Temperature constant at 35°C):

0.156

0.1575

0.159

0.1605

0.162

0.1635

0.206 0.289 0.366

Co

nd

ucta

nce

(S

)

Concenteration (M)

T= 35°C


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RESULT

• The relevant graphs shows that the 1 / Resistance of an electrolyte increases at a steady rate as the temperature increases.

• Also, Conductivity vs. Concentration graphs increase Linearly at a constant given temperature of an electrolyte.


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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 increase in temperature. Hence, the result of the experiment agrees with reasoning.

• On increasing the concentration of the electrolyte the conductivity increases due to increase in number of ions of solute i.e increase in no. of ions of CuSO4 and ZnSO4. Solvent i.e water is kept constant at 150 mL.


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PRECAUTIONS • Variation of resistance due to one of the factors should

be kept constant.

• The electrodes used in each case should always be kept parallel to each other.

• The solution should be kept undisturbed throughout the experiment.

• For each observation, three readings are taken and the mean value is considered.

• The distance between the electrodes should be kept constant.

• Thermometer’s bulb should be suspended completely into the solution.

• The solute should be completely dissolved in water.

• The electrodes should not touch each other and the distance between them should be constant.


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BIBLIOGRAPHY BOOKS: • Chemistry (Part I) – Textbook for Class XII; National

Council of Educational Research and Training

• Concepts of Physics 2 by H C Verma; Bharti Bhawan(Publishers & Distributors)

WEB LINKS: • www.icbse.com • http://www.jenway.com/adminimages/A02_001A_Effect_of

_temperature_on_conductivity.pdf • http://www.researchgate.net/ • http://www.emedicalprep.com/study-

material/chemistry/electro-chemistry/electrolytic-conductance-factors.html

• en.wikipedia.org • http://chem-guide.blogspot.in/2010/04/variation-of-

conductivity-with.html

http://www.icbse.com/

http://www.jenway.com/adminimages/A02_001A_Effect_of_temperature_on_conductivity.pdf

http://www.jenway.com/adminimages/A02_001A_Effect_of_temperature_on_conductivity.pdf

http://www.researchgate.net/

http://www.emedicalprep.com/study-material/chemistry/electro-chemistry/electrolytic-conductance-factors.html



http://en.wikipedia.org/

http://chem-guide.blogspot.in/2010/04/variation-of-conductivity-with.html

http://chem-guide.blogspot.in/2010/04/variation-of-conductivity-with.html

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Chem Project 12