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Sodium thiosulphate solution (5-25 %)
because sunlight can affect its stability
Titrate each solution separately with solution of known concentration of sodium thiosulphate. The titre value will give the amount of thiosulphate reacted with iodine, hence you can find concentration of iodine.
· In analytical chemistry, sodium thiosulphate is used for the determination of the strength of a given solution of iodine. · Sodium thiosulphate is preferred in iodometric analysis due to the fact that sodium thiosulphate is oxidized by iodine. It is also used to determine the strength of many oxidizing agents.
it is a secondary solution because it can change its concentration by absorbing moisture....
Because it is :)
yes it does..... it also produces an odur which is sulphur from the thiosulphate.
To ensure the stability of the solution
Sodium thiosulphate solution (5-25 %)
Sodium thiosulphate solution (5-25 %)
because sunlight can affect its stability
Titrate each solution separately with solution of known concentration of sodium thiosulphate. The titre value will give the amount of thiosulphate reacted with iodine, hence you can find concentration of iodine.
· In analytical chemistry, sodium thiosulphate is used for the determination of the strength of a given solution of iodine. · Sodium thiosulphate is preferred in iodometric analysis due to the fact that sodium thiosulphate is oxidized by iodine. It is also used to determine the strength of many oxidizing agents.
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.
This reaction may be misunderstood as a direct reaction between the thiosulphate and iodate ions , however, in practice an iodide and acid mediated production of iodine from the iodate is used to react with the thiosulphate. A standard reaction used to calibrate a solution of sodium thiosulphate is as follows: Acid and potassium iodide are added to a solution of potassium iodate getting the following reaction: KIO3 + 5KI + 3H2SO4 = 3I2 + 3K2SO4 + 3H2O represented by the following ionic equation: IO3- + 5I- + 6H+ = 3I2 + 3H2O Thiosulpathe is titrated against this solution (effectively against iodine): I2 + 2Na2S2O3 = Na2S4O6 + 2NaI represented by the following ionic equation: I2 + 2S2O32- = S4O62- + 2I- where the dark brown coloured solution of iodine turns pale yellow and finally colourless as the reaction proceeds (starch is used as indicator after the pale yellow transition forming a black solution due to an iodine-starch complex which turns colourless upon further addition of thiosulphate).
No. because it contains water of crystallization so it can absorb or release water..
it is a secondary solution because it can change its concentration by absorbing moisture....