Conductometric Titration

SANDIP UNIVERSITY CHEMISTRY CIA:3 (PowerPoint Presentation) Topic : Conductometric Titration

Made By : Vidya Kumari Class :B-Tech(FE) “C” Roll No. : 02 Guided By : Dr. Shilpa Sharma

CONDUCTOMETRIC TITRATION! WHAT IS IT?

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It is a method in which we determine the point where reaction is completed with the help of a conductometer that measures the changes in conductance of solution produced by the ions in the solution . Conductometer works on the principle of ohm’s law

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V = IR

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V = VOLTAGE, I = ELECTRIC CURRENT, R = ELECTRICAL RESISTANCE

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If we are to find the strength of a acid then we take that acid into a beaker and dip the electrode of conductometer into the acid solution. This measures the conductance of acid. Now, we titrate this acid solution against the base of known molarity, the conductance starts decreasing. This is due to the binding of H+ Acid with the OH- of base until a point is reached where conductance is minimum. When we move forward the conductance starts increasing again. This is now due to the free ions of Base present in solution.

The Conductance of the solution depends on: •

Size of the ions:

The conductivity of the solution is inversely proportional to the size of the ions ,if the size of the ions is increasing then the conductivity of the solution will decrease because the mobility of the ions will decrease by increasing the size of the ions. So the mobility of the hydrogen ions will be greater then the sodium ions so the conductance of the solution containing sodium ions will be less than the solution containing hydrogen ions. •

Temperature:

By increasing the temperature, the mobility of the ions in the solution will increase. So temperature has a direct effect on conductance of solution. E.g. by increasing the temperature the conductance will increase and vice versa.

How is Conductometric Titration done PROCEDURE •

100 Ml of acid was taken in beaker.

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Solution was kept at room temperature for at least 10 minutes.

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Then Dip the electrode of conductometer in solution.

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Measure the initial conductance of solution.

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First reading of conductometer was noted.

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Then this solution was titrated against the Base solution of known strength using burette.

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Observe the change in conductance of acid solution after every 5 ml addition of base.

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Plot these values to find the equivalence point.

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Volume of base used till the equivalence point is the volume which is required to fully neutralize the acid.

Types of Conductometric Titration •

Strong Acid-Strong Base

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Strong Acid-Weak Base

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Weak Acid-Strong Base

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Weak Acid-Weak Base

APPLICATIONS •

Check water pollution in rivers and lakes .

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Alkalinity of fresh water .

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Salinity of sea water (oceanography) .

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Deuterium ion concentration in water- deuterium mixture.

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Food microbiology- for tracing micro organisms.

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Tracing antibiotics .

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Estimate ash content in sugar juices .

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Purity of distilled and de - ionised water can determined .

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Solubility of sparingly soluble salts like AgCl,BaSo4 can be detected.

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Determination of atmospheric so2,etimation of vanillin in vanilla flavor.

ADVANTAGE OF CONDUCTOMETRIC TITRATIONS: 1. Does not require indicators since change in conductance is measured by conductometer 2. Suitable for colored solutions 3.Since end point is determined by graphical means accurate results are obtained with minimum error 4. Used for analysis of turbid suspensions, weak acids, weak bases, mix of weak & strong acids

DISADVANTAGES OF CONDUCTOMETRIC TITRATION: 1. Increased level of salts in solution masks the conductivity changes , in such cases it does not give accurate results 2. Application of conductometric titrations to redox systems is limited because, high concentrations of hydronium ions in the solution tends to mask the changes in conductance