1. Calculate the required mass of sodium thiosulphate:
- Molar mass of Na2S2O3.5H2O = 248.19 g/mol (with 5 moles of water of crystallization)
- Molarity (M) = Normality (N) = 0.01 N
Mass (w) of Na2S2O3 required = Molarity (M) x Molecular weight x Volume (in liters)
w = 0.01 x 248.19 g/mol x 1 L
= 2.482 g
2. Preparation of the 0.01N Sodium Thiosulphate solution:
- Weigh 2.482 g of sodium thiosulphate pentahydrate (Na2S2O3.5H2O) accurately using an analytical balance.
- Transfer the weighed sodium thiosulphate to a clean and dry 1000 mL volumetric flask.
- Add a small amount of distilled water to dissolve the sodium thiosulphate. Swirl the flask gently to ensure complete dissolution.
- Once the sodium thiosulphate is dissolved, add more distilled water to the volumetric flask until the volume reaches the 1000 mL mark. Swirl the flask thoroughly to ensure uniform mixing.
3. Standardization of Sodium Thiosulphate Solution:
Before using the prepared sodium thiosulphate solution for analytical purposes, it is essential to standardize it against a primary standard. The standardization process involves reacting the sodium thiosulphate with a known concentration of potassium dichromate (K2Cr2O7) solution and calculating the exact concentration of the sodium thiosulphate solution.
Remember to follow the appropriate safety guidelines when handling chemicals and lab procedures, including proper use of personal protective equipment (PPE). Always refer to the specific protocol or instructions provided for your intended application or experiment.
