Preparation of 1N Ethanolic Potassium Hydroxide (KOH)

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Preparation of 1N Ethanolic Potassium Hydroxide:

Reagent:

Phenolphthalein Solution:

Dissolve 1 gm of phenolphthalein in 100ml of alcohol (95%).

95% Alcohol:

Mix 95 ml absolute alcohol with 5ml of water.

Preparation Of 1N Ethanolic Potassium Hydroxide:

  1. Dissolve 68gm of potassium hydroxide in 20ml of water.
  2. Add aldehyde-free ethanol to make 1000 ml.
  3. Allow the solution to stand in a tightly stoppered bottle for 24 hrs.
  4. Quickly decant the clear supernatant into a suitable tight container.

For lower strengths follow below-given table:

StrengthQuantity of KOH (in g)Addition of Water (in ml)Mae up with aldehyde-free ethanol (in ml)Reference
0.1N6.8201000USP
0.2N14201000USP
0.5N34201000USP
Lower Strength Ethanolic Koh Preparation

Standardization of Ethanolic Potassium Hydroxide (KOH):

  1. Accurately measure about 25ml of 1N Hydrochloric acid VS.
  2. Dilute with 50ml of water.
  3. Add 2 drops of phenolphthalein solution.
  4. Titrate the solution with 1N Ethanolic potassium hydroxide solution.
  5. The permanent pink color is produced.
Preparation of 1N Ethanolic Potassium Hydroxide
Preparation of 1N Ethanolic Potassium Hydroxide

Calculation of Ethanolic Potassium Hydroxide (KOH):

Normality of Ethanolic KOH = 25 x N / V

  • Where,
  • N=Normality of Hydrochloric acid
  • V= Volume of Potassium Hydroxide consumed in ml.

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