Interested to Buy Any Domain ? << Click Here >> for more details...
When starch reacts with iodine, why does it create the
characteristic blue-black colour?
- 5 Answers
- 21153 Views
- Hetero, Pace Pharmaceuticals, I also Faced
- E-Mail Answers
Answer Posted / mallikarjun
This reaction starts from a solution of hydrogen peroxide with sulfuric acid. To this is added a solution containing potassium iodide, sodium thiosulfate, and starch. There are two reactions occurring in the solution.
In the first, slow reaction, the triiodide ion is produced .
H2O2(aq) + 3 I−(aq) + 2 H+ → I3 + 2 H2O.
In the second, fast reaction, triiodide is reconverted to iodide by the thiosulfate.
I3(aq) + 2 S2O32−(aq) → 3 I−(aq) + S4O62−(aq)
After some time the solution always changes color to a very dark blue, almost black.
When the solutions are mixed, the second reaction causes the triiodide ion to be consumed much faster than it is generated, and only a small amount of triiodide is present in the dynamic equilibrium. Once the thiosulfate ion has been exhausted, this reaction stops and the blue color caused by the triiodide – starch complex appears.
| Is This Answer Correct ? | 2 Yes | 4 No |
Post New Answer View All Answers
What is xylose? What is its chemical formula?
What is the property of Alkaline earth metal Ions?
What are respectively some remarkable functions of immunoglobulin?
why ph is not more than 14?
What is the bond angle of phosphorous?
What are respectively some remarkable functions of reverse transcriptase?
Explain and define standard feat of formation
What does hess law states?
Why does physical exertion increase symptoms of poisoning by trematol?
What is Sublimation energy?
Why can it be said that the enzymatic action is highly specific?
How do we prepare diborane?
Define ionic product of water. What is its value?
Give the type of functional group, general formula, and the suffix for methanoic acid (or) formic acid.
How do you define free radical addition reaction? Give an example.
