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Specialty Chemistry Forums => Other Sciences Question Forum => Topic started by: JZ_1 on August 14, 2005, 11:27:05 PM

Title: banana and isopropyl alcohol
Post by: JZ_1 on August 14, 2005, 11:27:05 PM

I hope this is random enough for you to answer this question in this forum :)

I was doing my HW while i felt hungry
hw:
http://www.chemicalforums.com/index.php?board=4;action=display;threadid=4284

i got a banana and i ate it..(dont worry this story is short)..then i put a few drops (5 or more) isopropyl alcohol on one of the inside peel of the banana .
i put water on another...

the alcohol was absorbed while the water was blocked (semi-permeable membrene)

the alcohol made the banana rot...i want to ask WHY???

..try this yourself .

also..i want to ask...HOW DO U DELETE A new topic...?

Title: Re:banana and isopropyl alcohol
Post by: billnotgatez on August 15, 2005, 03:51:24 AM

Interesting experiment!
I think this entry could also have been posted in Citizen Science Forum.

I try to eat bananas regularly so I might try this experiment.

Did you use household or reagent isopropyl?

Regards,
Bill

Title: Re:banana and isopropyl alcohol
Post by: ATMyller on August 15, 2005, 05:46:38 AM

Isopropyl alcohol dissolves cell membranes' lipides. You'll get similar result with other nonpolar solvents etc. gasoline.

Title: Re:banana and isopropyl alcohol
Post by: JZ_1 on August 16, 2005, 03:55:10 PM

Since it is nonpolar.....how do they keep the water...in the isopropyl alcohol mixed..(ie: 70% isopropyl alcohol by volume…active indegredient also contains water).

are u suggestin gthey are tricking you, giving you less for your money?

http://en.wikipedia.org/wiki/Isopropanol
LOOK under uses...how does it dissolve water??

"The isopropanol does not remove the water from the gasoline. Rather, the isopropanol solublizes the water in the gasoline..."

???

Title: Re:banana and isopropyl alcohol
Post by: Yggdrasil on August 16, 2005, 04:32:29 PM

Whether a solvent is non-polar or polar is not an either/or sittuation.  There is a continuous scale of polarity.  Isopropanol can be considered a polar solvent.  The hydroxide group creates enough of a dipole for it to interact with many polar groups, and the hydroxide also enables it to hydrogen bond to (making is a protic solvent as well).  However, the hydrocarbon chain gives it some qualities of a non-polar solvent as well.  Therefore, isopropanol is still a polar solvent, but it is considerably less polar than water.  Isopropanol can still disolve water (probably because of its ability to hydrogen bond), but since it has some non-polar characteristics, it can disolve some organic compounds that are insoluble in water -- for example, membrane phospholipids (in the OP's example) or pen ink.  Similarly, since it is less polar than water, isopropanol cannot disolve some highly polar/ionic compounds that are soluble in water, such as NaCl.

Title: Re:banana and isopropyl alcohol
Post by: Dude on August 16, 2005, 05:31:54 PM

How quickly does the banana turn black and rot after exposure to IPA?  Dissolution of a lipid should not discolor the banana.  I would suspect that the IPA triggers some type of enzymatic ripening process similar to ethylene.

Title: Re:banana and isopropyl alcohol
Post by: Yggdrasil on August 16, 2005, 06:35:31 PM

My guess that the phenomenon JZ_1 observed is not rotting, but bruising.  Bruising comes about when the membrane-bound structures (such as the vacuoles) within a plant are ruptured (lysed).  Since the IPA will dissolve membrane phospholipids, it will cause lysis.  But, this is just my guess, and I'm not completely sure this explanation is correct.

Title: Re:banana and isopropyl alcohol
Post by: JZ_1 on August 17, 2005, 03:22:50 PM

yea..it may probably be brusing...

but it doesnt bruise quickly...itz kind of an over time thing...2 min... i dunno

i'm out of bananas ...hehe...