Learn about the preparation and standardization of 0.1 M oxalic acid solution through a laboratory experiment or practical.
Aim:
To prepare and standardize 0.1 M oxalic acid solution using 0.1 M solution of sodium hydroxide.
Requirements:
Glasswares: Burette, burette stand, conical flask, volumetric pipette, beaker, volumetric flask, funnel, glass rod, wash bottle, etc.
Chemicals: LR grade oxalic acid (C2H2O4), sodium hydroxide (NaOH), phenolphthalein indicator, etc.
Apparatus: Digital/analytical balance
Principle:
This titration is based on alkalimetry titration. When a strong base is titrated with a weak acid, the salt formed in the reaction that is not entirely hydrolyzed, and the pH of the final solution is about 07.00. Oxalic acid is a weak acid and is standardized by titration with a strong base, NaOH. To determine the endpoint phenolphthalein is used as an indicator. When NaOH is titrated with oxalic Acid, the following reaction occurs.
Preparation of 1M oxalic acid solution:
Weigh accurately 126.07 gm of oxalic acid and add 500 ml of distilled water. Once it has completely dissolved, make up the volume to 1000 ml.
Preparation of 1M NaOH solution:
Weigh accurately 40.00 gm of sodium hydroxide and add 500 ml of distilled water. Once it has completely dissolved, make up the volume to 1000 ml.
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 10.00 ml of prepared 1M NaOH solution and pour it into a conical flask.
- Add 2-3 drops of phenolphthalein indicator.
- Titrate the sample solution with the oxalic acid solution until the pink color disappears.
- Properly record the readings of the burette.
- To get accurate results, repeat the titration three times.
- Take their mean and calculate the molarity of oxalic acid.
Observation table:
|
Sr. No. |
Content in conical flask |
Burette reading |
Volume of titrant used (ml) |
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Initial |
Final |
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1 |
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2 |
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3 |
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Mean: |
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Calculations:
The Molarity of Oxalic Acid is calculated using the formula : M1V1=M2V2
where ,
V1 is the volume of 1M NaOH solution = 10 ml
M1 is the molarity of NaOH solution = 1M
V2 is the volume of oxalic acid solution
M2 is the molarity of oxalic acid =?
Therefore, M2=M1V1/V2
Result:
The strength of the prepared oxalic acid solution was found to be_____M.
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