Sciencemadness Discussion Board

Cleaning glassware

Fossil - 15-4-2012 at 08:03

I have recently started using highly concentrated acids and am wondering as to what is the best way to clean the glassware that was containing the acid.

Any help is appreciated.

Fossil - 15-4-2012 at 08:22

I should add, is it still alright to neutralize with a sodium bicarbonate solution?

kristofvagyok - 15-4-2012 at 08:40

Quote: Originally posted by Fossil  
I should add, is it still alright to neutralize with a sodium bicarbonate solution?


The concentrated acid should be poured on bicarbonate until the solution is neutral or basic.

Or just simply wash with large amount of water. Simply.

If there is any organic stuff left in it, than wast with acetone, methanol, or Caro's acid, simply and the best.

After the peroxo-sulfuric acid it should be washed again with large amount of water....

But hadn't this question been answered million times?:P

Fossil - 15-4-2012 at 09:23

I'm not sure if it has, but I was wondering what I should do when I cant get all of the acid out, for example concentrated hydrochloric acid on the walls of a R.B.F. Normally i'll just pour some sodium bicarbonate solution in, but I don't want to take any chances with high concentration acids.

So im wondering if the procedure is the same or if there is a special technique.

Endimion17 - 15-4-2012 at 10:28

Quote: Originally posted by Fossil  
I'm not sure if it has, but I was wondering what I should do when I cant get all of the acid out, for example concentrated hydrochloric acid on the walls of a R.B.F. Normally i'll just pour some sodium bicarbonate solution in, but I don't want to take any chances with high concentration acids.

So im wondering if the procedure is the same or if there is a special technique.


What do you mean by "I can't get all of the acid out, for example HCl"?
Hydrochloric acid is not a sticky goo that clings to the glass walls. Wash the flask with tap water, rinse twice with distilled water and you're good to go.

If you're experiencing droplets clinging to the walls, your flask is greasy. Wash it with detergent first. Always finish with double rinsing with distilled water. That way you prevent the buildup of limescale.

Fossil - 15-4-2012 at 11:31

I did not mean that the HCl is sticking to the walls, but the inside is wet with HCl. When you pour water in there, lots of vapors come out, Cl2 vapors if i'm not mistaken.

I'm wondering if there's another way of washing glassware that is wet with acid, other than a NaHCO3 solution. If there isn't, i'm just going to keep using NaHCO3 solution to clean acid.

bob800 - 15-4-2012 at 13:52

That vapor is just a mist of HCl droplets dispersed in air. I don't understand the trouble you're having with the acid "wetting" your beaker; just rinse it out with some water from the tap...

kristofvagyok - 15-4-2012 at 14:36

Quote: Originally posted by Fossil  
I did not mean that the HCl is sticking to the walls, but the inside is wet with HCl. When you pour water in there, lots of vapors come out, Cl2 vapors if i'm not mistaken.


HCl is not a big deal, SO2, Cl2, NOCl2, BCl3, organic haloacids and a lot other thing is much worse. Usually when I'm working with HCl, sometimes 37% or with pure gas I just wash the glassware with some water and it's okay.

If you are hypersensitive to acid fumes, then get a gas mask, even carbon filter get's out most of the harmful fumes.

Or work with dilute solutions, or just simply skip the "preparative" chemistry if you are afraid of the acids.

P.S.: the HCl doesn't turn into chlorine, if there is no strong oxidizer next to it;)

Fossil - 15-4-2012 at 14:45

My concern is that whenever I wash out containers that have HCl in them with water, strong vapors are emitted that burn the sinuses.

I was just wondering if there are other methods of washing other than water or an NaHCO3 solution.

barley81 - 15-4-2012 at 14:49

You could try using more dilute acid which fumes less. Or, use diluted sulfuric acid, which doesn't fume at all.

Endimion17 - 15-4-2012 at 16:35

I really don't see the problem here. It's just hydrochloric acid mist soluble in water. Pour in small amount of water in the flask, close it with a cork, shake it up, unplug it, discharge the liquid into the drain. Repeat if neccessary.
You don't have to fill it up with water, letting the mist creep out.

Hexavalent - 28-4-2012 at 13:54

In my experience, adding some sand, followed by vinegar, and magnetically stirring and/or boiling in the offending container works wonders - its often cheaper than the HCl method and I have found it to work where other methods fail.

Endimion17 - 29-4-2012 at 05:42

Quote: Originally posted by Hexavalent  
In my experience, adding some sand, followed by vinegar, and magnetically stirring and/or boiling in the offending container works wonders - its often cheaper than the HCl method and I have found it to work where other methods fail.


That's a great way to screw up borosilicate glassware. Sand is harder than lab glass.

Pyridinium - 2-5-2012 at 20:21

Quote: Originally posted by kristofvagyok  

The concentrated acid should be poured on bicarbonate until the solution is neutral or basic.


@krisofvagyok: I'm not sure if you meant it this way, but as presented, that's dangerous. Concentrated acid poured onto dry bicarbonate is an acid spatter waiting to happen.

@Fossil: if you use cold water, there is less chance to drive out HCl vapors. They will stay dissolved. If you are getting HCl vapors driven out of the beaker by the sudden influx of water, try using a spray mist of cold water.

If HCl is clinging to the glass after that, then soak it in cold water for a while.

When working with concentrated HCl you should have good ventilation anyway.

kristofvagyok - 3-5-2012 at 12:57

Quote: Originally posted by Pyridinium  
Quote: Originally posted by kristofvagyok  

The concentrated acid should be poured on bicarbonate until the solution is neutral or basic.


@krisofvagyok: I'm not sure if you meant it this way, but as presented, that's dangerous. Concentrated acid poured onto dry bicarbonate is an acid spatter waiting to happen.


Yep, You are absolutely right! One word is missing: solution.

Pour the acid to a a bicarbonate solution until it's not fizzing.

DJF90 - 3-5-2012 at 14:23

Dont use sand to clean your glassware. Use salt and acetone. NaCl is insoluble and acts as a mild abrasive on stains, while acetone does a number on most organic gunk. Sitting it on the mag stirrer for a while can help with stubborn marks/stains. Failing that, go for a base bath. Works every time for me, even where aqua regia fails. Flasks always come out looking so bright and shiny, just like new.