0.1 M Edta Solution Preparation And Standardisation

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Jul 05, 2024

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0.1 M EDTA Solution Preparation and Standardization

EDTA (Ethylene Diamine Tetraacetic Acid) is a widely used chelating agent in various fields, including chemistry, biology, and medicine. In analytical chemistry, EDTA is used as a titrant to determine the concentration of metal ions, particularly calcium and magnesium, in water and other samples. In this article, we will discuss the preparation and standardization of 0.1 M EDTA solution.

Preparation of 0.1 M EDTA Solution

To prepare 0.1 M EDTA solution, the following materials are required:

Materials:

• EDTA disodium salt (C10H14N2O8S2.2H2O)
• Distilled water
• pH paper or pH meter
• Sodium hydroxide (NaOH) solution (1 M)

Procedure:

1. Weighing: Weigh 3.72 g of EDTA disodium salt accurately using a balance.
2. Dissolution: Transfer the weighed EDTA to a 100 mL beaker and add approximately 50 mL of distilled water.
3. Dissolving: Heat the mixture gently on a hot plate or in a warm water bath to dissolve the EDTA completely.
4. pH Adjustment: Check the pH of the solution using pH paper or a pH meter. If the pH is too low, add a few drops of 1 M NaOH solution to adjust the pH to around 7-8.
5. Dilution: Transfer the solution to a 100 mL volumetric flask and make up to the mark with distilled water.
6. Mixing: Mix the solution thoroughly to ensure uniform concentration.

Standardization of 0.1 M EDTA Solution

To standardize the prepared 0.1 M EDTA solution, we need to determine its exact concentration using a primary standard, such as calcium carbonate (CaCO3).

Materials:

• Calcium carbonate (CaCO3) powder (primary standard)
• Distilled water
• pH paper or pH meter
• Indicator solution (e.g., Eriochrome Black T or Patton and Reeder's indicator)

Procedure:

1. Weighing: Weigh accurately a known amount of CaCO3 powder (approximately 0.25 g) using a balance.
2. Dissolution: Dissolve the weighed CaCO3 in 50 mL of distilled water in a 100 mL beaker.
3. Titration: Add a few drops of indicator solution to the CaCO3 solution and mix well.
4. Titration with EDTA: Slowly add the prepared 0.1 M EDTA solution to the CaCO3 solution while stirring until the color of the indicator changes (e.g., from pink to blue).
5. Endpoint: Record the volume of EDTA solution added at the endpoint.
6. Calculation: Calculate the exact concentration of the EDTA solution using the following formula:

Molarity of EDTA = (Weight of CaCO3 x 2) / (Volume of EDTA x Molecular weight of EDTA)

Example Calculation:

Let's assume the weight of CaCO3 is 0.25 g, and the volume of EDTA solution required for titration is 25 mL.

Molarity of EDTA = (0.25 g x 2) / (25 mL x 292.24 g/mol) = 0.099 M

The exact concentration of the EDTA solution is 0.099 M.

Conclusion:

In this article, we have discussed the preparation and standardization of 0.1 M EDTA solution. The prepared solution can be used as a titrant for the determination of metal ions, particularly calcium and magnesium, in water and other samples. The standardization of the EDTA solution is crucial to ensure accurate results in subsequent titration reactions.