Sciencemadness Discussion Board

Storage under water.

CaCl2 - 1-2-2017 at 05:22

There are certain chemicals (Phosphorus etc.) that are often stored in water, but this has the problem that eventually the water evaporates. (Unless you store it in a sealed ampoule, but then the water is generally kind of pointless.)


I wonder if you could use deliquescent salts to prevent evaporation of water.
A salt to be used so would need to be:
-Colourless
-Strongly deliquescent
-Unreactive towards most things.


This could be especially useful for element collections, since they usually have to be stable for years if not decades.

Tsjerk - 1-2-2017 at 05:58

Get a properly capped bottle and the water won't evaporate.

CaCl2 - 1-2-2017 at 06:42

Quote: Originally posted by Tsjerk  
Get a properly capped bottle and the water won't evaporate.

Getting really tiny bottles with good caps is very difficult.

For example, for element collections that only have limited space for each element, especially for phosphorus which has many (4?) allotropes.

This would also provide protection from accidentally uncapped/badly capped bottles

Chlorine - 1-2-2017 at 07:02

I've never had a problem with water evaporation. I've had a 2g chunk of red phosphorus from my element collection stored under 20ml of water for about 4 months. As long as you put some sort of tape in the threads (Teflon, electrical, ChemiResist, etc) you should be fine.

CaCl2 - 1-2-2017 at 07:37

Quote: Originally posted by Chlorine  
I've never had a problem with water evaporation. I've had a 2g chunk of red phosphorus from my element collection stored under 20ml of water for about 4 months. As long as you put some sort of tape in the threads (Teflon, electrical, ChemiResist, etc) you should be fine.

OK, Well enough closed bottles seem to work.
Still, I wonder if using a hydroscopic salt would work for my specific situation.


The bottles I am using are very tiny, the smallest of these:
http://www.ebay.co.uk/itm/131612123546?_trksid=p2057872.m274...

Since their caps are made from cork, I used a 3D printer (In a library) to make plastic caps, but they aren't perfectly airtight even with added glue.

fluorescence - 1-2-2017 at 10:52

Either use a more expensive bottle, refill your stuff, so maybe a larger bottle with more water and check on it once in a while. For comparison, as I don't want any of my salts to get wet I check the caps of every bottle every three weeks, unscrewing them and rescrewing them to make sure nothing gets in or out.
I guess the answer for you question is just store it better but the actual side question was more interesting actually ... you asked for a low evaporation.
One thing I could think of is an ionic liquid maybe, they usually don't evaporate at all as they have nearly no vapour pressure. Well P4 is quite reactive so you need to check a lot before doing that but it would be an interesting question...Also for element samples you don't use frequently but want to protect them well enough...

j_sum1 - 1-2-2017 at 11:25

There is an irony in someone named CaCl2 discussing storage under water. :D

unionised - 1-2-2017 at 12:23

Quote: Originally posted by j_sum1  
There is an irony in someone named CaCl2 discussing storage under water. :D

He's not wrong.

CaCl2 would work nicely.

CaCl2 - 3-2-2017 at 03:43

Yes, it seems like CaCl2 would work...


It even has the additional benefit of significantly lowering the freezing point of water. (So glass bottles won't crack if stored in a cold place.)

vmelkon - 4-2-2017 at 06:39

Quote: Originally posted by Chlorine  
I've never had a problem with water evaporation. I've had a 2g chunk of red phosphorus from my element collection stored under 20ml of water for about 4 months. As long as you put some sort of tape in the threads (Teflon, electrical, ChemiResist, etc) you should be fine.


Does red phosphorus need to be stored under water?

CaCl2 - 4-2-2017 at 10:11

Quote: Originally posted by vmelkon  
Quote: Originally posted by Chlorine  
I've never had a problem with water evaporation. I've had a 2g chunk of red phosphorus from my element collection stored under 20ml of water for about 4 months. As long as you put some sort of tape in the threads (Teflon, electrical, ChemiResist, etc) you should be fine.


Does red phosphorus need to be stored under water?

I think generally only white phosphorus requires that.

Chlorine - 4-2-2017 at 18:57

Quote: Originally posted by CaCl2  
Quote: Originally posted by vmelkon  
Quote: Originally posted by Chlorine  
I've never had a problem with water evaporation. I've had a 2g chunk of red phosphorus from my element collection stored under 20ml of water for about 4 months. As long as you put some sort of tape in the threads (Teflon, electrical, ChemiResist, etc) you should be fine.


Does red phosphorus need to be stored under water?

I think generally only white phosphorus requires that.


You should store all allatropes of phosphorus under water.

CaCl2 - 5-2-2017 at 05:31

Quote: Originally posted by Chlorine  
Quote: Originally posted by CaCl2  
Quote: Originally posted by vmelkon  
Quote: Originally posted by Chlorine  
I've never had a problem with water evaporation. I've had a 2g chunk of red phosphorus from my element collection stored under 20ml of water for about 4 months. As long as you put some sort of tape in the threads (Teflon, electrical, ChemiResist, etc) you should be fine.


Does red phosphorus need to be stored under water?

I think generally only white phosphorus requires that.


You should store all allatropes of phosphorus under water.

Why?, most sources seem to suggest non-white phosphorus is air stable and non-toxic.

Even the sciencemadness wiki says water isn't required.

Honestly asking why they should be stored under water, not saying you are wrong.

Metacelsus - 5-2-2017 at 06:08

At my academic research, I recently used a bottle of Raney nickel that had been stored under water for at least 4 years. The cap was sealed with Parafilm, and less than 1 mL of water had evaporated. The Raney nickel was still good.

As a side note, if you ever use Raney nickel, watch out for it sticking to stir bars (it's somewhat magnetic). I nearly started a fire when I removed my stir bar from the reaction flask.

PirateDocBrown - 5-2-2017 at 12:00

I once had a 100g bottle of red P that had been clearly filled in the 80's. It was opened and used in the early 2000s, and was still good. It had never had water in it. It was just a standard dry reagent bottle, no wax or parafilm of any sort.

DrP - 9-2-2017 at 08:03

Quote: Originally posted by CaCl2  
Quote: Originally posted by Tsjerk  
Get a properly capped bottle and the water won't evaporate.

Getting really tiny bottles with good caps is very difficult.

For example, for element collections that only have limited space for each element, especially for phosphorus which has many (4?) allotropes.

This would also provide protection from accidentally uncapped/badly capped bottles


Can you use paraffin or PTFE tape around the seal of the cap? Put it on the outside of the bottle (inside of the cap) and screw the cap over it - The water wont evaporate out past that paraffin seal. Might work... will certainly buy you time at least.