Page 46 - Chemistry - XI

EXPERIMENT - 18

Objective

To determine the strength of a given solution of dilute HCl by titrating it against a standard solution of 0.05
M sodium carbonate.

Materials Required
Burette (50 mL), pipette (25 mL), conical fl ask (250 mL), burette stand, funnel, white glazed tile, measuring
fl ask, Na CO , hydrochloric acid, and methyl orange solution
3
2
Indicator
Methyl orange

End Point
Yellow to pink

Procedure
1. Prepare 0.05 M standard solution of Na CO as per the above experiment.
2
3
2. Rinse the clean burette with the given HCl solution.
3. Fit a burette on the stand and fi ll it nearly up to zero level or up to your eye level with HCl solution.

4. Remove the air gap if any from the burette by running the solution forcefully from the burette nozzle
and again adjust the burette reading at zero level.
5. Pipette out 25 mL of Na CO solution in a titration fl ask.
2
3
6. Add 3–5 drops of methyl orange as an indicator.
7. Continue adding HCl from the burette till the yellow colour of the solution becomes pink. Note down

the fi nal reading of the burette.
8. Record your observations in the tabular form.
9. Repeat the procedure till two concordate readings are obtained.

Observation Table
Burette readings

S. Initial Final Volume of HCl used Volume of Na CO 3 Concordant
2
No. reading reading in mL (Final-Initial) solution taken in mL reading
1.
2.
3.
4.
5.

Calculations

M V = 2M V M = Molarity of acid
1 1 2 2 1
(Acid) (Base) V = Volume of acid (from burette)
(Acid) (Base)
1

44