Standardization of sodium thiosulphate by potassium iodate?

Answer 1

what is the procedure of standardization of Sodium thiosulphate (0.025N)with potassum dichromate (0.25N)

Answer 2

In this titration method, a solution of potassium iodate is used as the titrant to determine the concentration of sodium thiosulfate solution. It involves adding potassium iodate to sodium thiosulfate solution until the reaction is complete, as indicated by the disappearance of the starch-iodine complex's blue color. The reaction is:

5Na2S2O3 + 2KIO3 + 2H2SO4 -> 2Na2SO4 + K2SO4 + 5I2 + 5H2O.

Answer 3

1. Firstly wash out a burette twice with distilled water.

2. Clean the washed burette with the approximately 0.1 mol dm-3 standardised sodium thiosulphate, which is going to be prepared.

3. Fill the burette with approximately 0.1 mol dm-3 standardised sodium thiosulphate, until the bottom of the meniscus is at the 0 cm3 mark on the burette.

4. Pipette 25cm3 of 0.020 mol dm-3 potassium Iodate solution into a 250 cm3 conical flask.

5. Using a 10cm3 measuring cylinder, measure out 10cm3 of 0.5 mol dm-3 potassium iodide and add it to the conical flask.

6. Using a 10cm3 measuring cylinder, measure out 10cm3of 1 mol dm-3 sulphuric acid and add it to the conical flask.

At this stage the three solutions will be mixed together in the conical flask, to produce iodine.

7. Record the initial reading on the burette (0 cm3) to work out the titre, record this to two decimal places

8. Turn the burette tap, so the 0.1 mol dm-3 sodium thiosulphate pours into the iodine in the conical flask (adding small amounts and then stirring the conical flask)

9. When the red/brown iodine solution in the flask turns yellow, stop titrating the 0.1 mol dm-3 sodium thiosulphate into the flask

10. Add a few drops of the starch indicator to the conical flask; it will turn dark blue/black colour to intensify the colour change.

11. Turn the burette tap back on, add the 0.1 mol dm-3 sodium thiosulphate drop wise, whilst swirling the flask, until the dark blue/black colour disappears.

12. Record the final burette reading, from the point where the bottom of the meniscus is.

13. Record the result in the table, and then calculate the titre value by finding the difference between the initial reading and the final reading.

14. Repeat the titration to obtain concordant results, whereby the titre is 0.1 cm3 difference at max.

15. Obtain all your results and present them in a table, to two decimal places.

Answer 4

add 25g of sodiun thiosulphate to 1litre of water of water to make it o.1N solution. Make it 0.01 by 1:10 dilution.

Answer 5

It is impossible to do correct chemical experiments or chemical analysis with substances having an unknown concentration.

Answer 6

using potassiumdichromate

Answer 7

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