Conductometry
Aim:-
Conductometric Titration
of mixture strong Acid (HCL) and weak acid (HAC) against strong base NaOH.
Apparatus:-
Conductometry Bridge, conductivity
cell, Beaker glass rod, Burette pipette etc.
Chemicals:-
0.1N HCL, 0.1N CH3COOH
0.5N NaOH.
Theory:-
Conductance measurements
are frequently employed to find the endpoint of acid-alkali and other
titration. The principle involved is that conductance depends upon the mobility
of ions.
When a mixture of a
strong acid and weak acid is to be titrated against a strong alkali a
combination of the curve is obtained suppose a mixture of HCL and CH3COOH
is to titrated against NaOH HCL being a much stronger acid (completely ionizes)
will get titrate first. The titration of acetic acid will come only after
HCL gets completely neutralized.
Calculation:-
1) Normality of HCL solution.
N1=N2V2/V2
2) Normality of acetic acid solution.
N1=0.5×(Y-X)/10
Grams/lit. Of CH3COOH solution
N1×equivalent weight of CH3COOH
Procedure:-
Pipette out 10ml of 0.1N
HCL and 10ml of 0.1N acetic acid in a beaker and dip the conductivity cell of
necessary add distilled water till electrodes dips in solutions then connect
the cell to the bridge and make other necessary connections. Fill the micro burette
with 0.5 N NaOH solution and add 0.2ml of each time from the micro burette into an acid solution taken in a beaker stir with a glass rod and determine its
conductance continue the observation for every 0.2 addition of NaOH solution
and record the corresponding conductance initially conductance decreases the
increase slowly and finally increases rapidly.
Sl. No |
Mixture of alkali |
Molar
conductance |
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Graph:-
Plot a graph of volume of alkali added (along X-axis) and conductance along (Y-axis), we get combination of the curve as shown in the nature of the graph while the point X corresponds to the neutralization of HCl the point Y corresponds to the neutralization of CH3COOH from the endpoint of the titration calculate the normality ion Grams /liter of HCL and CH3COOH.
Nature of Graph:-
Result:-
1) Normality of HCL solution…..
2) Grams/lit of HCL ………
3) Normality of CH3COOH…….
4) Grams /lit of CH3COOH……
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