Month: March 2018

Estimation of Magnesium ions in water using EDTA

Estimation of Magnesium ions in water using EDTA

The principle on which the titration lab is based:

The reaction between Mg2+ ions and EDTA can be represented like this.

Mg2+ + H2Y2- → MgY2- + 2H+

Prepare a standard solution of magnesium sulfate and titrate it against the given EDTA solution using Eriochrome Black T as the indicator. A buffer solution is prepared for maintaining the pH of about 10. When the reaction is complete all the magnesium ions would have been complexed with EDTA and the free indicator would impart a blue color to the solution. Estimation of magnesium ions using edta.

Procedure:

Preparation of 0.025M MgSO4.7H2O:  Dissolve 0.616 grams of analytic grade magnesium sulfate into a 100 mL volumetric flask. Dissolve the salt completely using distilled or de-ionized water.

Standardization of EDTA: 20 mL of the standard magnesium sulfate solution is pipetted out into a 250 mL Erlenmeyer flask and diluted to 100 mL . Add 2 mL of a buffer solution of pH 10. Add 4 drops of Eriochrome Black T to the solution. The solution is warmed to 40 degrees C and titrated against EDTA taken in the burette. At the end point the color changes from wine red to blue. Repeat titrations for concordant values.

Estimation of magnesium ions in the given sample: 20 mL of the given sample of solution containing magnesium ions is pipetted into a 250 Erlenmeyer flask, the solution is diluted to 100 mL, warmed to 40 degrees C, 2 mL of a buffer solution of pH 10 is added followed by 4 drops of Eriochrome black T solution. The solution is titrated against the standardized EDTA solution. Repeat the titrations to obtain concordant values. The end point is the color change from red to blue.

Using the volumes of solutions used, their determined molarity, you will be able to calculate the amount of magnesium in the given sample of water.

This is how you can perform an estimation of magnesium using edta.

Benzoic Acid From Benzyl Chloride

Preparation of Benzoic Acid From Benzyl Chloride

Preparation of Benzoic Acid from Benzoyl chloride

In this reaction a side chain oxidation is performed. In order to achieve this benzyl chloride is mixed with sodium carbonate solution and is oxidized with potassium permanganate solution. The sodium salt of benzoic acid is formed, this is acidified with concentrated hydrochloric acid when benzoic acid crystallizes out. Preparation benzoic acid benzyl chloride

Benzoic acid benzyl chloride
Preparation of Benzoic acid from Benzyl Chloride

 

 

 

 

 

Reagents
  • Benzyl chloride 2 ml
  • Anhydrous sodium carbonate 2 g in 20 ml of water
  • Potassium permanganate 8 g in 80 ml water
Procedure:

About 2 ml of benzyl chloride is added to a solution of about 2 g rams of anhydrous sodium carbonate dissolved in 20 ml of distilled water. The mixture is taken in a round bottom flask. The round bottom flask is fitted with a water refulx condenser and heated . 4 gams of potassium permanganate in 80 ml of water is added in small quantities through the water condenser until a permanent pink color persists even after continuous boiling. It is boiled for about 1 hour. The mixture is not transferred to a beaker. About 4 grams of sodium sulfite are added to this mixture. Now add concentrated hydrochloric acid to this solution until the solution is acidic. The solution is cooled, precipitated benzoic acid is filtered and washed. The acid is recrystallized from boiling water.
The yield of benzoic acid is about 2 grams and the melting point is 1210C
Care should be taken while setting up the equipment’s, the hydrochloric acid used in converting the sodium salt of benzoic acid is concentrated, so extreme care should be taken while handling the chemicals and using them. Wear goggles , gloves and apron while performing the experiment. Use common sense while performing any lab activity and read your lab manual before doing any experiment.

 

 

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