Explain the method of preparation and standardization of 500ml 0.1M sodium hydroxide? Please help me. Please reply my question.

Question

It is a titration with potassium hydrogen phthalate using phenolphthalein as indicator

Answer 1

Preparation of 0.1 M NaOH (500 mL):

1. Molar mass of NaOH = 40 g/mol

2. Required amount = 0.1 mol/L × 0.5 L = 0.05 mol

→ Weigh 2.0 g NaOH

3. Dissolve 2.0 g NaOH in 100 mL distilled water in a beaker.

4. Transfer to a 500 mL volumetric flask, rinse beaker with distilled water, and make up the volume to 500 mL.

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Standardization (Titration):

Primary standard: Potassium hydrogen phthalate (KHP)

Indicator: Phenolphthalein

Procedure:

1. Weigh ~0.2042 g of KHP (MW = 204.2 g/mol) – equals 0.001 mol.

2. Dissolve in 50 mL distilled water in a conical flask.

3. Add 2–3 drops of phenolphthalein (colorless in acid).

4. Fill burette with NaOH solution.

5. Titrate until solution turns pale pink (endpoint).

6. Repeat to get concordant values.

7. Calculate exact molarity of NaOH using:

M_{\text{NaOH}} = \frac{W_{\text{KHP}} \times 1000}{204.2 \times V_{\text{NaOH}}}

Where:

: weight of KHP in g

: volume of NaOH used in mL