Starch
Starch indicator is added after sodium thiosulphate in iodometric titrations to help visualize the endpoint of the reaction. Starch reacts with any excess iodine produced at the endpoint, forming a dark blue-black color, allowing for easier detection of when all the thiosulphate has reacted.
Standardization of a known concentration sodium thiosulfate solution is necessary to accurately determine its exact concentration. This process helps to correct for any variations in concentration that may have occurred during preparation or storage, ensuring that precise measurements can be made in subsequent experiments or analyses.
Starch acts as an indicator for the endpoint of the reaction between sodium thiosulphate and potassium iodate, as it forms a blue-black complex with iodine. This color change helps identify when all the iodine has been liberated from the reaction. This method is commonly used in titrations to determine the concentration of the sodium thiosulphate solution accurately.
Sodium thiosulphate is typically white in color, appearing as a crystalline powder or solid.
because sodium thiosulphate is unstable and iodine also so to maintain neutral medium we have to use sodiumcarboate
Sodium thiosulphate solution (5-25 %)
The boiling point of sodium thiosulphate is 100 degrees Celsius, the same as water.That would be 212 degrees Fahrenheit.
In standardization of sulfuric acid against sodium carbonate, the indicator typically used is phenolphthalein. Phenolphthalein turns pink in basic solutions, which helps in determining the endpoint of the reaction between sulfuric acid and sodium carbonate.
sodium chloride, sulphur, sulphur dioxide and water
Sodium thiosulfate is not conductive because it does not dissociate into ions in solution. It is a non-electrolyte.
The chemical symbol for sodium thiosulphate (hypo) is Na2S2O3•5H2O.
In iodometry sodium thiosulphate is used because it is standardized by potassium dichromate and it is the best and relaible way to standardized sodium thiosulphate using iodometric titration. Infact sodium thiosulphate is also standardized by iodimetry. The difference between both of them is only of iodine. In iodometry iodine gas is liberated that will further react with sodium thiosulphate but in iodimetry standard solution of iodine is used.