Estimation of Sodium benzoate by Non aqueous titration

Estimating the amount of sodium benzoate in a non-aqueous solution can be achieved by using non-aqueous titration. Here are the steps to estimate the amount of sodium benzoate using non-aqueous titration:

1. Preparation of the sample solution: Weigh accurately about 0.1-0.2 g of the sodium benzoate sample and dissolve it in 25 ml of non-aqueous solvent such as methanol or ethanol. Mix it well.
2. Preparation of titrant solution: Prepare a standard solution of a strong base like potassium hydroxide (KOH) in a non-aqueous solvent such as methanol or ethanol. The concentration of the titrant should be known and verified.
3. Titration: Add a few drops of phenolphthalein indicator to the sample solution. Phenolphthalein turns pink in the presence of a base. Titrate the sample solution with the standardized KOH solution until the pink color persists for at least 30 seconds. The volume of KOH solution used is noted.
4. Calculation: The amount of sodium benzoate in the sample can be calculated using the following formula:

Amount of sodium benzoate = (volume of KOH solution x normality of KOH x molecular weight of sodium benzoate) / weight of the sample

Where, normality of KOH = (concentration of KOH x 1000) / molecular weight of KOH

The molecular weight of sodium benzoate is 144.1 g/mol, and the molecular weight of KOH is 56.11 g/mol.

By using this method, one can estimate the amount of sodium benzoate present in a non-aqueous solution accurately.

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