cleaning potassium permanagate stains

[dolphinscales]

good day to you all

what are your sure fired ways of cleaning potassium permanagate stains from glassware please.

[rae]

0.1 M oxalic acid works a treat!!

[dolphinscales]

of course the one i have not tried - lol thanks for that and for such a quick answer to bless you

[franco]

Hi Annette,
Try 0.1M acidified ferrous sulfate too - make up 0.1 mole ferrous sulfate solution and add sufficient 1M sulfuric to give a pale green colour).
Cheers,
Fran

[RosalieM]

I know a lot of people have said Oxalic Acid works well for cleaning glassware, but I don't seem to have much success with it. I have tried a few times with different concentrations. My current 'project' in the prep room is sorting out droppers. A lot of the glass tubes are white with residue on the inside of them. I have tried the oxalic acid and it doesn't seem to have worked. Also tried HCl and H2SO4 and nappisan on previous occassions. Does anyone have any better ideas I could try? Does anyone else have this same problem with glass tubes from their droppers?

[Labbie]

I use good old bleach over night. Of course rinse well, if they are not clean over night, I throw them out. Also the white caps come up a treat.

[Ocker]

The white in droppers, means they have been used in Sodium Hydroxide that actually etches the glass, Just keep them for Na OH or Chuck them

[RosalieM]

I don't think they are only sodium hydroxide but could be... I've put them all in bleach and will see what happens when I rinse and dry them tomorrow. I have soaked these tubes in oxalic acid, then soaked in water, agitated them by hand in the sink and then allowed them to dry. When I put the bleach in, one of them went purple! Must have still had indicator in it after all that... Makes me wonder what's the point of washing them! (I'm changing over to lids on the dropper bottles instead of keeping the droppers in, hence the big 'wash up').

[trish armstrong]

So will oxalic acid also be great to clean out pipettes too????
I have alot with white stuff that has been in them for years, they get pushed to the back of the draw????
Trish

[RosalieM]

Hi Trish,
Try these links to other discussions (if they work!) on cleaning burettes - might give you some ideas to try.

http://www.chemtalk.com.au/viewtopic.ph ... ette#p1550

http://www.chemtalk.com.au/viewtopic.ph ... it=burette

[Ocker]

Also I use pipe cleaners obtained from craft shops and always have some broken Guitar strings (the finer ones) for cleaning tips of burettes & pipettes

[Wombat]

The brown stain left by KMnO4 is the reduction product MnO2 formed when the KMnO4 oxidises some organic material on the glassware for example. The best way to remove this is to reoxidise the MnO4 with acidified hydogen peroxide. Just a few drops of say 2M HCl or 1M H2SO4 in some 3-6 Volume% peroxide (or even weaker) works a treat.
This reminds me of the way I used to clean my stained coffee cup at work - add a few drops of acid to the cup and then fill the cup with dilute permanganate. Pour out the permanganate and rinse. The stain looks worse, but then add a few drops of acid and fill with dilute peroxide - hey presto back to new.

[RosalieM]

OK this may sound really random, but I had some dropper bottles that I was close to throwing out because they wouldn't come clean - tried napisan, oxalic acid, sulfuric, nitric and hydrochloric acids (not all at once of course!) and a few other things, scrubbing etc... and yesterday I was getting a prac ready and accidently picked up one of those instead of a nice clean one to put some lemonade in. The lemonade bubbled up way more than I would have expected, so I grabbed a test tube brush, scrubbed a little, rinsed the bottle and put it on the rack to dry. I now have a good-as-new dropper bottle!! So I tried the others today and they are now clean!! I might try soaking those dropper tubes (the ones I haven't thrown yet) in lemonade after the holidays. So there you go! Who would have picked lemonade as a cleaning agent???

[Jen1]

Gee, and coke has such a bad reputation, never knew lemonade was as fierce!

[macca]

O.K. I thought the Lemonade may have been a delayed April Fools Joke.
I put some disgusting test tube in Lemonade, + some in a concentrate Citric Acid solution (one of the ingredients in the lemonade). Could not believe the citric acid ones, Limewater stains just peeled off infront of my eyes overnight Lemonade did well, but the citric acid little to no effort to get clean, Just the way I like it

[Labbie]

Great, lemomade wins again. Thanks for the tip on Cirtic acid.

[smeee]

p. 67 of "The Laboratory" says to soak in 10% aqueous oxalic acid solution. Works for me but thanks for the lemonade tip....more
" environmentally friendly "

[Sassi]

Here is another interesting one...

I had some stained stock bottles, ferric chloride & pot perm stains that I had tried everything on (But I never treid the lemonade one, I love it) and nothing worked, so I gave up. A few weeks ago I needed a bottle to make up some protein solution, and all I had left was those yukkie stained ones So I had to use it, I made my peptone solution. Next morning I came in to give the teacher her solution, well the solution had turned black, but miraculously all the stains were gone!!!! Not a single mark was left

Can someone please explain that one? I mean I can understand the lemonade one, at least that is an acid, but a protein??? How would that work?


Sassi

[sunray18]

Sometimes Bicarb Soda then vinegar does a good job too.. cheap!
Oh for the old Chromic Acid ... sigh....
NOTHING resisted that!

[vlclabbie]

Hi guys! Hope everyone had a great holiday (although I know some are still lazing around on the beach....!),

We have some pot. permanganate stains on the bench - any fixes for that??

Thanks!