What indicator should be used in an iodine thiosulfate titration?
What indicator should be used in an iodine thiosulfate titration?
starch
The indicator that is usually chosen for titrations involving iodine (triiodide) is starch. Starch forms a dark blue complex with iodine. The end point in iodimetry corresponds to a sudden color change to blue.
What is the indicator in the titration of hypochlorite with thiosulfate?
The indicator is added to signal the endpoint of the titration, that is, the endpoint of the reaction of thiosulfate with iodine. Starch serves as an indicator because it forms a dark blue complex with iodine, but that complex disappears (turning the blue solution colorless) when all the iodine is used up.
What happens when iodine is titrated with thiosulfate solution?
The iodine solution, which is a golden-brown colour, can be titrated against sodium thiosulfate solution. When it reaches a pale yellow colour, a few drops of a freshly prepared starch solution are added. The solution becomes blue-black, and the titration is continued until it goes colourless.
What color is thiosulfate?
Sodium thiosulfate
| Names | |
|---|---|
| Chemical formula | Na 2S 2O 3 |
| Molar mass | 158.11 g/mol (anhydrous) 248.18 g/mol (pentahydrate) |
| Appearance | White crystals |
| Odor | Odorless |
How to calculate thiosulfate by iodate titration?
O n (iodate) = n(thiosulfate)/6 C(iodate) x V(iodate) = C(thiosulfate) x V(thiosulfate)/6 Pipette out a 25 mL aliquot of the standard potassium iodate solution into a conical flask and add 10 mL of 10% sulfuric acid solution and 2 g of KI.
How to prepare thiosulfate pentahydrate for an indicator?
2. Prepare a 0.1-M thiosulfate solution by dissolving approximately 25 g of sodium thiosulfate pentahydrate (Na2S2O3·5H2O; FW 248.19) in the sodium carbonate solution. Transfer the solution to a clean storage bottle, and store the solution in the dark. 3. The next three steps involve preparation of the indicator.
How is sodium thiosulphate used for redox titration?
1. Rinse and fill a clean burette with 0.1 M sodium thiosulphate solution that is to be standardised. Make sure that there are no air bubbles in your burette. 2. Record the initial reading of your burette. (Note: You should read your burette at eye level. Accuracy of reading the burette reading should be within the range of + 0.05 mL).
How big is a titre of sodium thiosulfate?
Concentration of sodium thiosulfate solution = 0.13 M. Specimen Results (standardising an iodine solution) Rough titre = 23.2 cm 3 Second titre = 23.1 cm 3 = 23.1 cm 3 Average of accurate titres = 23.1 cm 3 Volume of iodine solution used in each titration = 25.0 cm 3 = 0.1 M Specimen Calculations.