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Engineering Chemistry Lab Experiments

Estimation of HCL by Conductometric Titrations


To determine the strength of the strong acid by titration with strong base Conductometrically

Apparatus Required:

Digital Conductivity meter, Conductivity cell, Burette, Beakers, Measuring Cylinder, Burette Stand etc.

Chemicals Required :

Sodium hydroxide (NaOH), Hydrochloric acid (HCl)

Principle :

At first solution contain H+ and Cl- ions. Since H+ions posses greater mobility it follows that the conductivity is mainly due to H+ ions. The addition of NaOH is represented by the equation.

HCl + NaOH ————> NaCl + H2O

As NaOH is added the H+ ions are removed.The conductivity decreases as Na+ ions do not process much mobility. SAs the neutralization point and solutions contains Na+ ions and Cl- ions and will have minimum conductance value. If NaOH is further added this will add OH- ions and so the conductivity increases.


A standard solution of 0.2N NaOH is prepared. Similarly 0.1N HCl is prepared. 20 ml of HCl is taken in a 100 ml beaker and to it 20 ml of distilled water is added and kept in a thermostat. The conductivity cell is washed with distilled water and rinsed with acid soln. The cell is kept in acid containing beaker and it is connected to the bridge.The conductivity of the soln is measured by adjusting the reading. NaOH soln is taken into burette and add 1 ml of soln to acid, stirred well and conductance is measured. Each time 1 ml of base is added to acid stirred well and the conductance is measured. For every instance. Equal numbers of values are taken on either side of the point of maximum. Repeat the procedure of addition of 1 ml NaOH and noting the conductivity of the resulting solution. Take 20-25 readings


Estimation of HCL by Conductometric Titrations


S. No Volume of NaOH (ml) Observed conductance (ms)


N1V1 = N2V2


The normality of strong acid (HCl) determined by titrating against a strong base (NaOH) =________N

Viva Questions:

1. When strong acid combines with a strong base what type of reactionoccurs?

2. Why conductance decreases on addition of NaOH to HCI ?

3. What is the unit for conductance?

4. How the end point for a particular reaction is calculated using this, titrationmethod?

5. How conductance is related to the concentration of the ions?