Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: cuso4 on 30/04/2003 21:30:49
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Just wondering, surgeons often used iodine solution to clean the wound on the patient, what properties of iodine make it a good disinfectant?
AG
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Good question - keep in mind that iodine is a member of Group VII along with chlorine and bromine which are also widely used for their sterilising qualities, most notably in swimming pools and spas. The chemistry behind the antiseptic properties is very similar, but iodine is a safer alternative being lower down the group and hence less reactive. Chlorine would not be nice to put on skin !
Chris
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How effective is Melaleuca Alternifolia (tea tree oil) compared to iodine?
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There is a show we did on 9th December 2001 which covers the antibacterial effects of Tea Tree Oil. Go to the archives and scroll down the page to 9th December 2001 Show and there should be a shortcut link to it from there.
It is extremely effective apparently, particularly against Staphs. I know many people use it on their skin because they find it can improve spots.
TNS
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I used it when i was younger on spots and found it much more affective than those creams like clearasil etc... it really stings if you add it directly to an open wound!
The only problem with iodine is that it stains everything brown and it never seems to come out! I had brown splodges on my school shirt for about a year (i did wash it by the way! [;)])
Essentia non sunt multiplicanda praeter necessitatem...
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Iodine solution is also famous for testing the presence of starch. Everyone know it turns blue/black, but why the colour change?
AG
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doesnt it form a complex with the starch and thus have different optical properties?
Essentia non sunt multiplicanda praeter necessitatem...
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Yes, you're right. The complex formed is called a starch-polyiodide complex. I found my notes...knew I had it somewhere...
AG
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The starch molecule forms a helical structure, the dimensions of which neatly accommodate iodine which can sit in the centre of the helix, complexing with the starch. This complex alters the optical properties of the molecule, making it absorb light and hence appear dark.
The most amazing thing is that it is a reversible reaction - the complex dissociates and the solution goes white again. Good question though, I learnt something !
TNS
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That's quite interesting! ^_^