Learn about the assay of sodium bicarbonate through a laboratory experiment or practical.
Aim:
To determine the percentage purity (assay) of sodium bicarbonate in a given sample using standard 1 N HCl.
Reference: USP Pharmacopoeia, USP31–NF26 Page 3240
Requirements:
Glasswares: Burette, burette stand, conical flask, volumetric pipette, beaker, volumetric flask, funnel, glass rod, and wash bottle, etc.
Chemicals: Sodium bicarbonate (NaHCO3), methyl red TS, and hydrochloric acid (HCL), etc.
Titration procedure:
- All glassware should be cleaned and dried according to standard laboratory procedures.
- Before filling the burette for the titration, rinse it with distilled water and then pre-rinse it with a portion of the titrant solution. Pre-rinsing is required to make sure that all solution in the burette is the desired solution, not a contaminated or diluted solution.
- Take the unknown stock solution of titrant in a clean and dry beaker then fill the burette using the funnel.
- Remove air bubbles from the burette and adjust the reading to zero.
- Take 03.00 gm of sodium bicarbonate and pour it into a conical flask, and mix with 100 ml of water.
- Then, as an indicator, add 2-3 drops of methyl red TS and properly mix it.
- Titrate the sample solution with standardized 1 N hydrochloric acid until the endpoint is reached.
- Add the HCl slowly, with constant stirring, until the solution becomes faintly pink.
- Bring the solution to a boil, then cool and repeat the titration until the faint pink color no longer fades after boiling.
- Properly record the readings of the burette.
- To get accurate results, repeat the titration three times.
- Take their mean and calculate the percentage purity of sodium bicarbonate.
- Each mL of 1 N hydrochloric acid is equivalent to 84.01 mg of NaHCO3.
Observation table:
Sr.
No. |
Content
in conical flask |
Burette
reading |
Volume
of titrant used (ml) |
|
Initial |
Final |
|||
1 |
|
|
|
|
2 |
|
|
|
|
3 |
|
|
|
|
|
Mean: |
Result:
The percentage purity of the sodium bicarbonate (NaHCO3) sample was found to be_____.
No comments:
Post a Comment