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A bottle of iodine solution used on apples to determine the correct harvest time. The chart shows the level of residual starch. The cut surface of an apple stained with iodine, indicating a starch level of 4–5. The iodine–starch test is a chemical reaction that is used to test for the presence of starch or for iodine. The combination of ...
The Minor test (also known as Minor's test, the starch–iodine test, and the iodine–starch test), described by Victor Minor in 1928, [1] is a qualitative medical test that is used to evaluate sudomotor function (perspiration or sweating).
The iodine clock reaction exists in several variations, which each involve iodine species (iodide ion, free iodine, or iodate ion) and redox reagents in the presence of starch. Two colourless solutions are mixed and at first there is no visible reaction. After a short time delay, the liquid suddenly turns to a shade of dark blue due to the ...
For simplicity, the equations will usually be written in terms of aqueous molecular iodine rather than the triiodide ion, as the iodide ion did not participate in the reaction in terms of mole ratio analysis. The disappearance of the deep blue color is, due to the decomposition of the iodine-starch clathrate, marks the end point.
English: Video of iodine clock reaction. Potassium persulphate is used to oxidize iodide ions to iodine, in the presence of starch and a small amount of thiosulphate ions. When the thiosulphate is exhausted (by reaction with the iodine produced), the dark blue iodine-starch complex is formed.
In an iodine clock reaction, colour changes after a time delay.. A chemical clock (or clock reaction) is a complex mixture of reacting chemical compounds in which the onset of an observable property (discoloration or coloration) occurs after a predictable induction time due to the presence of clock species at a detectable amount. [1]
Starch is optionally added as an indicator to show the abrupt increase in iodide ion concentration as a sudden change from amber (free iodine) to dark blue (the "iodine-starch complex", which requires both iodine and iodide.) [7] Recently it has been shown, however, that the starch is not only an indicator for iodine in the reaction. [8]
This is an accepted version of this page This is the latest accepted revision, reviewed on 9 January 2025. This article is about the chemical element. For other uses, see Iodine (disambiguation). Chemical element with atomic number 53 (I) Iodine, 53 I Iodine Pronunciation / ˈ aɪ ə d aɪ n, - d ɪ n, - d iː n / (EYE -ə-dyne, -din, -deen) Appearance lustrous metallic gray solid, black ...