Standardization of 0.1 N KOH Solution: Formula and Procedure
Introduction
KOH (Potassium Hydroxide) is a strong base that is widely used in various industrial and laboratory applications. In analytical chemistry, a standardized solution of KOH is often required for titrations, pH adjustments, and other reactions. In this article, we will discuss the standardization of 0.1 N KOH solution, its formula, and the procedure for standardization.
What is 0.1 N KOH Solution?
A 0.1 N KOH solution is a solution that contains 0.1 equivalents of potassium hydroxide per liter of solution. The normality (N) of a solution is defined as the number of equivalents of solute per liter of solution. In the case of KOH, one equivalent is equal to 56.11 grams of KOH (molecular weight of KOH).
Formula for Standardization of 0.1 N KOH Solution
The standardization of 0.1 N KOH solution involves titrating the KOH solution with a primary standard acid, such as potassium hydrogen phthalate (KHP). The formula for standardization is as follows:
Formula:
Normality of KOH solution (N) = (Weight of KHP (g) x Number of equivalents of KHP) / (Volume of KOH solution (L) x Molecular weight of KOH)
Where:
- Weight of KHP (g) is the weight of potassium hydrogen phthalate used for titration
- Number of equivalents of KHP is 1 (since KHP has one equivalent per molecule)
- Volume of KOH solution (L) is the volume of the KOH solution used for titration
- Molecular weight of KOH is 56.11 g/mol
Procedure for Standardization of 0.1 N KOH Solution
Apparatus:
- Volumetric flask (1 L)
- Pipettes (10 mL and 50 mL)
- Burette (50 mL)
- Erlenmeyer flask (250 mL)
- KHP (primary standard acid)
- Phenolphthalein indicator
- Distilled water
Procedure:
- Preparation of KHP Solution: Weigh approximately 2-3 grams of KHP accurately and transfer it to a 250 mL Erlenmeyer flask. Add about 100 mL of distilled water to the flask and stir until the KHP is completely dissolved.
- Preparation of KOH Solution: Weigh approximately 5-6 grams of KOH accurately and transfer it to a 1 L volumetric flask. Add about 500 mL of distilled water to the flask and stir until the KOH is completely dissolved. Dilute the solution to the mark with distilled water.
- Titration: Pipette 10 mL of the KHP solution into a 250 mL Erlenmeyer flask. Add 2-3 drops of phenolphthalein indicator to the flask. Titrate the KHP solution with the KOH solution from the burette until the pink color of the indicator just disappears.
- Calculation: Record the volume of KOH solution required for titration. Calculate the normality of the KOH solution using the formula above.
- Repeat the Titration: Repeat the titration process at least three times to ensure accurate results.
By following this procedure, you can standardize a 0.1 N KOH solution accurately. The standardized solution can then be used for various analytical applications, such as titrimetry and pH adjustments.
