To determine the strength and normality of a given acid solution (approx. 𝑁/10 HCl) by titrating it against standard 0.5 NaOH solution conductometrically.
Requirements: Conductometer, Conductivity cell, Beaker, Burette, Pipette, 0.1N HCl, Standard NaOH
Theory: In conductometric titrations, the conductance of electrolytic solution is measured with the help of a conductometer. When we titrate the strong acid with a strong base, in the starting the conductance is high and then decreases till endpoint end after endpoint the conductance is increases.
HCl + NaOH → Na+ Cl- + H2O(l)
Procedure:-
- Take a definite volume (20 ml) of given 0.1 N HCl in a beaker. Adding distilled water so that the electrodes of conductivity cell completely dip in the solution.
- Wash the conductivity cell with distilled water, dip in HCl solution and connect it to conductometer.
- Noted the conductance.
- Rinse and fill the burette with 0.5 NaOH solution.
- Now mix 0.5 ml of NaOH solution from the burette into beaker containing HCl solution. 6. After each addition, stir the contents thoroughly and note down the conductance.
- Repeat the procedure.
Volume of given acid solution taken = 20 ml
Normality of standard NaOH = 0.5N
Calculations:-
Suppose volume of NaOH required for neutralization = V2 ml
Plot volume of NaOH (in ml) along x-axis, and the observed conductance along y-axis.
By using normality equation ,
N1V1 = N2V2
(HCl) (NaOH)
N1 × 20 = 0.5 × V2
∴ N1 is normality of given HCl = 0.5 ×V2/20 = y
∴ Strength of HCl = Normality × eq. wt. of HCl
= N1 × 36.5 = y × 36.5
= W g/litre
Precautions:-
- The apparatus should be rinsed and cleaned properly before use.
- Rinse the electrodes of the conductivity sell thoroughly before starting the experiment.
- After each mixing of the NaOH, the solution should be thoroughly stirred.
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