Preparation and standardization of potassium Hydroxide (KOH)

Preparation and standardization of potassium Hydroxide:

Here we will understand how to do preparation and standardization of potassium hydroxide (KOH) as per USP.

Reagents required:

95% V/V Alcohol: Mix 95 ml of absolute alcohol into 5 ml of water.

Phenolphthalein Solution: Dissolve 1 g of phenolphthalein in 100ml of 95% alcohol.

Preparation of 1 N potassium hydroxide (KOH):

  1. Take 100 ml of volumetric flask.
  2. Dissolve 68 g of potassium hydroxide.
  3. Add freshly prepared saturated solution of barium hydroxide until no more precipitate forms.
  4. make up the volume to 950 ml.
  5. Allow it to stand overnight in a stoppered bottle.
  6. Decant the clear liquid or filter the solution in a tight polyolefin bottle.

For lower strength, the solution can be prepared as follows;

Quantity of KOH in gAddition of water in mlStrength of KOH
34 9500.5 N
13.69500.2 N
6.89500.1 N
3.49500.05 N
0.689500.01 N
Preparation of KOH

Standardization of 1 N KOH Solution:

  1. Dry the potassium biphthalate in 120°c for 2 hrs.
  2. Weigh previously crushed 5 g of potassium biphthalate in 75 ml of water.
  3. Add 2 drops of phenolphthalein solution.
  4. Titrate the solution with 1 N potassium hydroxide.
  5. The solution produces a permanent pink color.

Calculation formula of 1N KOH:


Normality of 1N KOH = ——————

0.20423 x V


W= Weight of potassium biphthalate in g

V= Volume of potassium hydroxide consumed in ml.

Preparation And Standardization Of Potassium Hydroxide
1N KOH Formula

Preparation and standardization of potassium Hydroxide (KOH) in pharmaceuticals.

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