Preparation of Standard Solution of Oxalic Acid

A standard of oxalic acid is a known high purity substance that can be dissolved to give a primary standard solution in a known volume of solvent. To prepare a particular quantity, a known solvent weight is dissolved. It is ready using a standard, such as a primary standard substance.

Aim:

To prepare the standard solution M/10 of oxalic acids.

Theory:

Hydrated oxalic acid = C₂H₂O₄.2H₂O

Molecular mass of Oxalic Acid = 126.

12.6 g of oxalic acid per litre of the solution should be dissolved to prepare M/10 oxalic acid solution.

On the other hand,

12.6 /4 = 3.15 g of crystals of oxalic acid should be dissolved in water and precisely 250 ml of the solution should be produced.

Materials Required:

1. Chemical balance
2. Watch glass
3. Weight box
4. 250ml beaker
5. Glass rod
6. 250ml measuring flask
7. Wash bottle
8. Weighing tube
9. Oxalic acid
10. Funnel
11. Funnel stand
12. Distilled water

Apparatus Setup:

Step by Step Laboratory Preparation of Standard Solution of Oxalic Acid

Procedure:

1. Take a watch glass, wash it with distilled water and dry it.
2. Weigh the exact amount of clean and dried watch glass and record its weight in the notebook.
3. Weigh correctly on the watch glass 3.15 g of oxalic acid and record this weight in the notebook.
4. Using a funnel, transfer oxalic acid softly and carefully from the watch glass into a clean and dry measuring flask.
5. Wash the watch glass with distilled water to move the particles that stick to it into the foam with the assistance of a wash bottle.
6. For this purpose, the volume of distilled water should not exceed 50 ml.
7. Wash funnels several times with distilled water to move the sticking particles into the measuring flask using a wash bottle. Add water in tiny quantities while washing the funnel. The distilled water quantity used for this purpose should not exceed 50 mL.
8. Using a wash bottle, wash the funnel carefully with distilled water to pass the solution attached to the funnel into the measuring flask
9. Turn the flask of measurement until the oxalic acid dissolves.
10. Using a wash bottle, thoroughly add enough distilled water to the measuring flask just below the etched mark on it.
11. Add the last few mL of distilled water drop into the measuring flask until the reduced meniscus level just touches the mark.
12. Put the stopper on the mouth of the flask and shake softly to make the entire solution uniform. Calculate it as a solution of oxalic acid M/10.

Observation:

Results:

250cm³ of decimolar or (M/10) solution of oxalic acid is prepared.

Precautions:

1. Weighing of oxalic acid crystals need weights of 2g + 1g + 100mg + 5mg.
2. Wash the watch glass carefully so that even a single crystal of oxalic acid is not left on the watch glass.
3. Last few drops should be added using a pipette to avoid extra addition of distilled water above the mark on the neck of the measuring cylinder.
4. If it is necessary to titrate oxalic acid or oxalate, add the required dilute H₂SO₄ amount and heat the flask to 60 °-70 ° C.