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Author: Subject: real problem pouring acids.
Jor
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[*] posted on 4-2-2008 at 07:33
real problem pouring acids.


Today, I've encountered some real concerns.
When I want to pour a small amount (say 20mL) of nitric or acetic acid in a graduated cylinder, I get the acid on my skin, every time (Also when I poured methanol, acetone, ethanol), because it will come down via the glass of the bottle. Even if I try to pour very quikly (when I do it to slow, It WILL get on me), still some drops go down the glass. I do not know how to solve this. Any advice?

PS: My hydrochloric acid and sulphuric are no problem at all: they are in HDPE containers and they are very easy to handle.
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YT2095
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[*] posted on 4-2-2008 at 07:38


time to invest in some Syringes / pipettes and fillers I think!

I trust you Always wear gloves and eye protection when doing this also?




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Jor
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[*] posted on 4-2-2008 at 07:58


yes, but still I will have to clean up the spills, wich takes time, and I will have to wash my gloves for a minute every time. I dont want pipettes and stuff in my main stock, as that will contaminate.
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[*] posted on 4-2-2008 at 08:08


Accept that while pouring liquids, there may be some spills along the outside of the test tube or beaker. I always pour acids IN the sink, which is ceramic in my lab and is not attacked by the acids. If your sink is sensitive for this, then put a thin layer of water in it, and do the pouring above that.

I alsways keep test tubes and the like in such a way, that no acid touches my hand/fingers. I even pour stuff like thionyl chloride in this way and I always have one or two drops going along the outside of the test tube, but I never had a drop of this liquid touch my hand (and I also don't want that, does not seem funny to me, as this stuff qickly reacts with water). I keep the test tube, or the beaker or erlenmeyer with two fingers and keep it at an angle of 30 degrees, such that the lower part of the test tube is directed away from both fingers (sad, that I cannot easily draw it over here) and in this position, pouring is not that bad. I also only have the liquid going along the test tube, and not going along the bottle from which I pour the liquid.

I agree with you, that I do not want anything like a pipette or so in the stock liquid, due to contamination. I hate the idea of that. The only liquid with which I do such things is with Br2. Br2 cannot be poured at all, because it forms a thin film of liquid on both the test tube (outside!) and the bottle from which it is poured. So that's the only liquid, I use a pasteur pipette for, one kept aside, which only is used for Br2 and never cleaned (the Br2 simply evaporates from it).




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YT2095
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[*] posted on 4-2-2008 at 08:19


Quote:
Originally posted by Jor
yes, but still I will have to clean up the spills, wich takes time, and I will have to wash my gloves for a minute every time. I dont want pipettes and stuff in my main stock, as that will contaminate.


I fail to see How it will contaminate?

and so what if it takes time, you should Never rush things in a Lab anyway, and Hygiene is always of utmost importance and never to be compromised on.

I use all glass pipettes here, and plastic disposable Syringes for not so aggressive chems.

never once had a problem with it.




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Klute
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[*] posted on 4-2-2008 at 08:51


Simply use a glass rod applied on the neck of your bottle to direct the flow of liquid into your beaker/bottle/whatever. Then tilt the bottle backwards before removing the rod from it's neck, so than no drops remain on the sides. No splashing or spills.
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Jor
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[*] posted on 4-2-2008 at 11:08


Quote:
Originally posted by YT2095
Quote:
Originally posted by Jor
yes, but still I will have to clean up the spills, wich takes time, and I will have to wash my gloves for a minute every time. I dont want pipettes and stuff in my main stock, as that will contaminate.


I fail to see How it will contaminate?

and so what if it takes time, you should Never rush things in a Lab anyway, and Hygiene is always of utmost importance and never to be compromised on.

I use all glass pipettes here, and plastic disposable Syringes for not so aggressive chems.

never once had a problem with it.

Well it does contaminate for me, as I cannot completely clean my pipettes (don't want to throw away after use). I clean them by sucking op distilled water a few times , and then let them dry.
And Klute, I will try the glass rod thing.

Especially acetone is a bitch to pour without spilling. But thats no concern.
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SecretSquirrel
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[*] posted on 4-2-2008 at 11:23


If you rinse the pipettes 4-5 times with tap water and then once more with distilled water, they should be sufficiently clean. Of course the chemical must be miscible with water. That's what I did when doing some qualitative analysis and I never had a false positive or negative reaction.

If you are still worried about contaminating your chemicals get some disposable PE pipettes and use each with its own solvent.

[Edited on 4-2-2008 by SecretSquirrel]

[Edited on 4-2-2008 by SecretSquirrel]
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[*] posted on 4-2-2008 at 13:24


Why not keep a pipette specifically for each chemical you need to dispense? No contamination that way.

I always use a glass pipette, with a rubber squeeze bulb for my acid. No choice really - ever tried to pour a few ml from a 10 litre bottle of nitric?

[Edited on 5-2-2008 by Twospoons]




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[*] posted on 4-2-2008 at 19:17


Quote:
Originally posted by Klute
Simply use a glass rod applied on the neck of your bottle to direct the flow of liquid into your beaker/bottle/whatever. Then tilt the bottle backwards before removing the rod from it's neck, so than no drops remain on the sides. No splashing or spills.


This guy has the best and simplest answer! I discovered this myself in a chemistry book from 1960. Not something mentioned in modern text from what I have seen:(:( This same book gave me ideas on improvised steam baths as well.

I use the glass rod technique alot. Not just for corrosives but fragrances. When I make soap and I don't want to spill my expensive fragrances, I use the rod to dispense by odorous components. It is easy to use down to 5 or 7ml of fluid.




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MadHatter
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[*] posted on 4-2-2008 at 19:47
Funnel


Like Woelen said, in the sink for openers - especially with acids ! I also like a small glass
or plastic funnel for slightly larger amounts.




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[*] posted on 4-2-2008 at 22:11


Plastic trays or shallow plastic tubs are useful when pouring corrosives. You can ignore minor spills for a bit, simple spritz drips off the container into the trays, and neutralise spills right in the tray.

As already said, funnels are good for keeping drips off the glassware being poured into, a glass rod is useful for reducing incidents of drips and dribbles, and dedicated pipetts and pour rods is a good way around contamination worries.
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woelen
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[*] posted on 4-2-2008 at 23:43


The glass rod method also is new to me, and I will certainly try that.

Another suggestion for Jor. Don't work directly from your stock containers. If you have e.g. 1 liter of conc. nitric acid, then take 50 to 100 ml and put that in a separate small glass bottle with a narrow neck (using a funnel). Work from this small bottle. You could use pipettes from this small bottle. If by accident there is some contamination, then at least you did not spoil your entire stock. I use this practice. I think I now have more than 100 small bottles which contain only tens of ml of liquid or several grams of solids and I use these. It works more conveniently, allows for safe (off-site) storage of bulk materials and I do not need to open the large containers every time (good for air-sensitive chemicals).




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[*] posted on 5-2-2008 at 04:52


It (stirring rod) doesn't always work perfectly. This seems to have something to do with the vagaries of the edges of certain bottles or perhaps the brain/world interface.

If you want to look very unprofessional like me, have a sacrificial rag around the mouth (of the bottle) when pouring nasty things to catch that drop that always seems to get away.
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[*] posted on 5-2-2008 at 09:26


If you are going to pour your acid from the stock container to another bottle as
suggested above, you can solve two problems at once by using a bottle which
has a pipette built into the cap. That way, there is no worry of remembering which
pipette goes with which chemical since they are automatically stored together.

http://www.hometrainingtools.com/catalog/chemistry/glassware...
http://store01.prostores.com/servlet/thescienceshop/the-1981...
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woelen
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[*] posted on 5-2-2008 at 09:49


I know that kind of droppers, but my experience with them is not really good. These things are made for medicine purposes and I once had such a bottle with nitric acid. The soft plastic cap was eaten away in a few days. It became brittle. I also used such a bottle for chloroform. The chloroform was gone in a few weeks (I must admit, it was a hot period in summer, but even then...). I only use these for pH indicator solutions now, which easily can be dripped in other liquids.



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[*] posted on 5-2-2008 at 10:02


I typically use the glass rod method, and for beakers and certain flasks when pouring cooperative liquids you can even do it one handed (I'll see if I can post a picture of the technique when I get home).

Taking small quantities of certain liquids and solids out of the stock container and storing them in appropriate smaller containers is probably my favorite method. However, it's very important to label them carefully (I always date every vial, bottle, etc. also... just to be sure). With liquids, make sure the label won't get washed away or bleached--sometimes a layer of clear packing tape is all it takes.

Also, 'Hello!' to everyone. (I've been reading for a couple days, but haven't posted until now.)
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[*] posted on 10-2-2008 at 09:45


Here's a bad picture of the one-handed method. Just rest the glass rod accross the diameter of the container, with a shorter length sticking off of the side you plan to pour from. Hold the glass rod with slight pressure from your index finger and pour. If you're using a beaker, rest one end of the glass rod in the pour spout as shown.

<img src="http://www.medievalsiege.net/bfesser/images/chem/pouring_technique.jpg" />

Also be sure you're wearing appropriate gloves for whatever you're working with.

[Edited on 2/10/08 by bfesser]
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Jor
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[*] posted on 5-3-2008 at 09:25


Sorry for the bump.

I advice you all really (if you didnt already have them) to buy pouring-rings (I translated straight out of dutch, so might be wrong translation). You put them on the outside of the bottle where the liquid comes out. They direct the flow of the liquid perfectly. Havent had any spills yet, when using them. This is how they look (icase you guys dont understand what i mean with pouring-rings):

http://www.pegelsoft.nl/index1.html?target=p1389.html
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[*] posted on 7-7-2008 at 23:58


I've been having the exact same problem, in fact I had a HCl spill the other day. I imagine the only thing scarier than an acid spill is an explosion/fire. Luckily, I didn't panic. I simply grabbed the baking soda and neutralized the mess.

I'll most definitely try the glass rod trick!




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[*] posted on 10-7-2008 at 22:44


Quote:
Originally posted by Jor
Quote:
Originally posted by YT2095
Quote:
Originally posted by Jor
yes, but still I will have to clean up the spills, wich takes time, and I will have to wash my gloves for a minute every time. I dont want pipettes and stuff in my main stock, as that will contaminate.


I fail to see How it will contaminate?

and so what if it takes time, you should Never rush things in a Lab anyway, and Hygiene is always of utmost importance and never to be compromised on.

I use all glass pipettes here, and plastic disposable Syringes for not so aggressive chems.

never once had a problem with it.

Well it does contaminate for me, as I cannot completely clean my pipettes (don't want to throw away after use). I clean them by sucking op distilled water a few times , and then let them dry.


This reminds me of an argument i had with an analytical chemist one day. I asked her if she was comfortable making a cup of tea in a beaker she had just cleaned ready for anyalytical work. She said she was not. I thought this absolutely ridiculous, what confidence do you have in your anaylsis then. She replied that something may leach into the tea that would not otherwise leach into her solutions. We were in an elevator, a stranger then interjected
'in which case you should wash everything with tea then'
If chemists can't be confident of being able to clean something when its important who can, there is no-one else, maybe we should pray.
I don't buy that contamination bit unless its a technique to protect yourself from yourself, knowing at times that you may take shortcuts on cleaning? In this case yes.




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[*] posted on 10-7-2008 at 23:18


Quote:

This reminds me of an argument i had with an analytical chemist one day. I asked her if she was comfortable making a cup of tea in a beaker she had just cleaned ready for anyalytical work. She said she was not. I thought this absolutely ridiculous, what confidence do you have in your anaylsis then.


Hmmm well I do like to get my glass very clean but I have had things stain it pretty good potassium permanganate does that pretty well but for the most part I wouldn't mind eating food out of labware.

I actualy think it would be a cool kitchen. Fry my eggs on a hotplate, boil my water in a RB flask in a heating mantle then use it to make my vacuum filtered coffee while magnetically stirring in the sugar.




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[*] posted on 11-7-2008 at 13:50


To avoid contamination I generally like to pour whatever liquid it is into another beaker first, then pipette from there.

Occasionally, if it is something particularly annoying to pour (like HF,) I'll assign it a large pipette that is only to be used for moving that liquid from the main to a smaller beaker, other pipettes are then used to move the liquid from the beaker to the reaction.




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[*] posted on 13-4-2012 at 04:45



When transferring Bromine from a Teflon coated bottle into a smaller bottle the glass rod trick will not work. The Br is actually repelled by the glass rod.
Why is that.
Would it be that Br has very high surface tension.
Would the glass rod trick work for Mercury?
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[*] posted on 13-4-2012 at 05:08


The glass rod certainly does not work for mercury. The meniscus of mercury is convex. Mercury does not stick to anything except some metals.
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