1. To Prevent Bacterial Growth:
* Sodium thiosulfate is susceptible to bacterial decomposition, especially in the presence of dissolved oxygen.
* Boiling the water removes dissolved oxygen, creating an anaerobic environment that inhibits bacterial growth.
* This helps to ensure the solution remains stable and maintains its chemical integrity for a longer duration.
2. To Remove Dissolved Gases:
* Boiling water also removes dissolved gases like carbon dioxide (CO₂).
* CO₂ can react with sodium thiosulfate, leading to the formation of sulfur dioxide (SO₂) and other byproducts, which can affect the solution's purity and stability.
3. To Remove Impurities:
* Boiling water helps to remove any impurities or particulate matter that may be present in the water, ensuring a cleaner solution for preparing the sodium thiosulfate.
4. To Improve Solubility:
* While not a primary reason, boiling water can slightly increase the solubility of sodium thiosulfate, allowing for a faster and more efficient dissolution process.
In Summary:
Preparing sodium thiosulfate solution in freshly boiled and cooled water ensures its stability, purity, and accuracy for various applications, especially in analytical chemistry and photographic processes.
