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 liter 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:

Preparation of Standard Solution of Oxalic Acid

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 funnel 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:

Weight of the watch glass W1g
Weight of the watch glass + Oxalic acid W1 + 3.15g
Weight of Oxalic acid 3.150g
Volume of distilled water 250cm3

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.

Viva Questions:

1. What technique is used to determine the strength of a given solution?

Ans: Strength determination is based on the equivalent law. Under this legislation, the amount of material equivalence to be titrated is equivalent to the amount of titrant equivalence used.

2. What is the standard solution?

Ans: The standard solution is called a solution of known concentration. A normal solution can be prepared by dissolving in a certain volume of the solvent a known amount of the substance.

3. What do you mean by “concordant readings”?

Ans: The reading in the volumetric analysis which differs by less than 0.05ml is known as concordant readings.

4. What is the difference between endpoint and equivalence point?

Ans: A titration equivalence point relates to a point where the added titrant is chemically equal to the sample analyte. On the other side, Endpoint is a point where the color of the indicator changes.

5. What is normal solution in the quantitative analysis?

Ans: A standard solution includes one solution equal per liter of solution. An appropriate for acid-base reactions is the quantity of a reactant that can generate or eat a mole of hydrogen ions using the concept of Brønsted-Lowry.