How to Prepare and Standardize Sodium Thiosulphate Solution

Table of Contents

1. Introduction
2. Preparation of Sodium Thiosulphate Solution
   • Materials needed
   • Weighing the sodium thiosulphate
   • Dissolving the sodium thiosulphate
   • Making up the solution to the desired volume
3. Standardization of Sodium Thiosulphate Solution with Potassium Dichromate
   • Preparation of potassium dichromate solution
   • Rinse and preparation of glassware
   • Filling the buret and conical flask
   • Adding potassium iodide and HCl solution
   • Titration process
   • Calculation of concentration
4. Observation Table
5. Preparation of N/80 Hypo Solution
   • Dilution method
   • Calculation for preparing N/80 hypo solution
6. Conclusion
7. FAQ

Preparation of Sodium Thiosulphate Solution

To prepare the sodium thiosulphate solution, you will need the following materials: sodium thiosulphate, a measuring flask, distilled water, and a funnel.

1. Start by weighing the required amount of sodium thiosulphate, which in this case is 2.48 grams.
2. Carefully transfer the weighed sodium thiosulphate into the measuring flask.
3. Rinse the funnel thoroughly and shake it well to ensure no residue is left.
4. Dissolve the sodium thiosulphate into the distilled water in the measuring flask. Shake it well until it is completely dissolved.
5. Once dissolved, make up the solution to the mark indicated on the measuring flask. In this case, the solution should reach 100 ml.

By following these steps, you will have successfully prepared the sodium thiosulphate solution.

Standardization of Sodium Thiosulphate Solution with Potassium Dichromate

To standardize the sodium thiosulphate solution using potassium dichromate, follow these steps:

1. Prepare the potassium dichromate solution by weighing 0.49 grams of potassium dichromate.
2. Transfer the weighed potassium dichromate into a clean funnel and rinse it properly.
3. Dissolve the potassium dichromate in a conical flask, ensuring it is completely dissolved.
4. Make up the solution to the mark indicated on the flask, which is 100 ml.
5. Rinse all the glassware thoroughly before use to ensure accurate standardization.
6. Fill the buret with the sodium thiosulphate solution, rinsing it with the solution.
7. Rinse the conical flask with the potassium dichromate solution.
8. Transfer 25 ml of the potassium dichromate solution into the conical flask.
9. Add 0.5 grams of potassium iodide to the conical flask and shake it.
10. Add 1 ml of concentrated HCl solution to the conical flask.
11. Observe the color change as iodine is liberated.
12. Keep the conical flask covered with a wrapped brown paper to protect it from direct sunlight.
13. Start titrating the potassium dichromate solution with the sodium thiosulphate solution until the dark brown color disappears.
14. Add a few drops of starch solution to the conical flask and continue titration.
15. Observe the color change to ensure complete titration of iodine.
16. Note down the final reading of the buret, which indicates the amount of sodium thiosulphate solution consumed.
17. Calculate the concentration of the sodium thiosulphate solution using the normality equation.

Observation Table

Preparation of N/80 Hypo Solution

The preparation of N/80 hypo solution involves a dilution method using the previously standardized N/10 sodium thiosulphate solution.

1. Take 12.5 ml of the N/10 sodium thiosulphate solution and transfer it to a measuring flask.
2. Make up the solution to the mark using distilled water in the measuring flask.
3. The measuring flask used should have a volume of 100 ml.
4. By following this method, you will obtain N/80 hypo solution.

Conclusion

In conclusion, sodium thiosulphate solution can be prepared by dissolving the required amount of sodium thiosulphate in distilled water. It can then be standardized using potassium dichromate through a titration process. The concentration of the sodium thiosulphate solution can be calculated using the normality equation. Additionally, N/80 hypo solution can be prepared through dilution using the standardized N/10 sodium thiosulphate solution.

FAQ

Q: What is the purpose of standardizing the sodium thiosulphate solution? A: Standardization is necessary to determine the precise concentration of the sodium thiosulphate solution, which is essential for accurate titration.

Q: Can I use any other material apart from potassium dichromate for standardization? A: Potassium dichromate is commonly used for standardization due to its stability and reliable results. However, other materials can be used depending on the requirements of the experiment.

Q: How does the hypo solution differ from the sodium thiosulphate solution? A: The hypo solution is a diluted form of the sodium thiosulphate solution, usually prepared for specific applications where a specific concentration is required.

Q: Can I use the sodium thiosulphate solution directly without standardizing it? A: Standardizing the sodium thiosulphate solution is important to ensure accurate results in any titration or analytical procedure. It helps establish the exact concentration of the solution.